U.S. patent number 6,649,313 [Application Number 10/283,283] was granted by the patent office on 2003-11-18 for photoreceptor, method of evaluating a photoreceptor, and method of producing the photoreceptor.
This patent grant is currently assigned to Ricoh Company, Ltd.. Invention is credited to Toshio Fukagai, Noriyuki Iwata, Toshiyuki Kabata, Takuji Katoh, Yuka Miyamoto, Katsuhiko Tani, Yoshio Watanabe, Junichi Yamazaki.
United States Patent |
6,649,313 |
Kabata , et al. |
November 18, 2003 |
Photoreceptor, method of evaluating a photoreceptor, and method of
producing the photoreceptor
Abstract
A photoreceptor including a support and a photosensitive layer
formed thereon, optionally an undercoat layer between the support
and the photosensitive layer, wherein when a group of data
consisting of N samples of the height x(t) (.mu.m) of a profile at
the interface of the support on the side of the photosensitive
layer, the interface of the photosensitive layer on the side of the
support, and/or the interface of the undercoat layer on the side of
the photosensitive layer, measured perpendicular to a horizontal
direction of the support, taken at .DELTA.t (.mu.m) intervals in
the horizontal direction, is subjected to Fourier transformation in
accordance with a formula as specified in the specification, in a
power spectrum obtained by the Fourier transformation, I(S)
represented by a formula specified in the specification has a
particular value, a method of evaluating the above photoreceptor, a
method of producing the photoreceptor, and an image formation
apparatus in which the photoreceptor is incorporated are
disclosed.
Inventors: |
Kabata; Toshiyuki (Kanagawa,
JP), Fukagai; Toshio (Shizuoka, JP),
Yamazaki; Junichi (Shizuoka, JP), Tani; Katsuhiko
(Tokyo, JP), Iwata; Noriyuki (Kanagawa,
JP), Katoh; Takuji (Kanagawa, JP),
Watanabe; Yoshio (Kanagawa, JP), Miyamoto; Yuka
(Shizuoka, JP) |
Assignee: |
Ricoh Company, Ltd. (Tokyo,
JP)
|
Family
ID: |
26583408 |
Appl.
No.: |
10/283,283 |
Filed: |
October 30, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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758193 |
Jan 12, 2001 |
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Foreign Application Priority Data
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Jan 12, 2000 [JP] |
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2000-004008 |
Jan 14, 2000 [JP] |
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2000-006769 |
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Current U.S.
Class: |
430/60;
430/56 |
Current CPC
Class: |
G03G
5/04 (20130101); G03G 5/10 (20130101); G03G
5/14 (20130101) |
Current International
Class: |
G03G
5/04 (20060101); G03G 5/10 (20060101); G03G
5/14 (20060101); G03G 015/04 () |
Field of
Search: |
;430/30,56,60 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Young; Christopher G.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. An image formation apparatus comprising a photoreceptor which
comprises a support and a photosensitive layer formed thereon,
wherein when a group of data of N samples of the height x(t)
(.mu.m) of a profile at the interface of said photosensitive layer
on the side of said support, measured perpendicular to a horizontal
direction of said support, taken at .DELTA.t(.mu.m) intervals in
said horizontal direction, is subjected to Fourier transformation
in accordance with formula (1): ##EQU182##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2)
##EQU183##
I(S) represented by formula (3): ##EQU184##
is calculated as being 6.0.times.10.sup.-3 or more, in which
coherent light is used as writing light for image formation.
2. The image formation apparatus as claimed in claim 1, wherein
said coherent light used writing light for image formation has a
spot diameter of 80 .mu.m or less.
3. The image formation apparatus as claimed in claim 1, wherein
said coherent light used writing light for image formation has a
spot diameter of 700 nm or less.
4. The image formation apparatus as claimed in claim 1, an image
for writing, which is produced by a multivalued gradation system is
output to said photoreceptor.
5. The image formation apparatus as claimed in claim 4, wherein
said image for writing has a resolution of 600 dpi or more.
6. An image formation apparatus comprising a photoreceptor which
comprises a support, an undercoat layer formed on said support, and
a photosensitive layer formed on said undercoat layer, wherein when
a group of data of N samples of the height.times.(t) (.mu.m) of a
profile of the surface of said undercoat layer on the side of said
photosensitive layer, measured perpendicular to a horizontal
direction of said support, taken at .DELTA.t(.mu.m) intervals in
said horizontal direction, is subjected to Fourier transformation
in accordance with formula (1): ##EQU185##
wherein n and m are each an integer, N=2.sup.P in which p is an
integer, in a power spectrum represented by formula (2)
##EQU186##
I(S) is calculated from formula (4): ##EQU187##
as being 6.0.times.10.sup.-3 or more, in which coherent light is
used as writing light for image formation.
7. The image formation apparatus as claimed in claim 6, wherein
said coherent light used writing light for image formation has a
spot diameter of 80 .mu.m or less.
8. The image formation apparatus as claimed in claim 6, wherein
said coherent light used writing light for image formation has a
spot diameter of 700 nm or less.
9. The image formation apparatus as claimed in claim 6, an image
for writing, which is produced by a multivalued gradation system is
output to said photoreceptor.
10. The image formation apparatus as claimed in claim 9, wherein
said image for writing has a resolution of 600 dpi or more.
11. An image formation apparatus comprising a photoreceptor which
comprises a support and a photosensitive layer formed thereon,
wherein when a group of data of N samples of the height x(t)
(.mu.m) of a profile of the surface of said support on the side of
said photosensitive layer, measured perpendicular to a horizontal
direction of said support, taken at .DELTA.t (.mu.m) intervals in
said horizontal direction, is subjected to Fourier transformation
in accordance with formula (1): ##EQU188##
wherein n and m are each an integer, N=2.sup.P in which p is an
integer, in a power spectrum represented by formula (2):
##EQU189##
I(S) is calculated from formula (4): ##EQU190##
as being 12.0.times.10.sup.-3 or more, in which coherent light is
used as writing light for image formation.
12. The image formation apparatus as claimed in claim 11, wherein
said coherent light used writing light for image formation has a
spot diameter of 80 .mu.m or less.
13. The image formation apparatus as claimed in claim 11, wherein
said coherent light used writing light for image formation has a
spot diameter of 700 nm or less.
14. The image formation apparatus as claimed in claim 4, an image
for writing, which is produced by a multivalued gradation system is
output to said photoreceptor.
15. The image formation apparatus as claimed in claim 14, wherein
said image for writing has a resolution of 600 dpi or more.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoreceptor which does not
produce abnormal images such as images including light and shade
stripes, and images including streaks, which are formed by the
multiple reflection of coherent light within the photoreceptor.
The present invention also relates to a method of evaluating the
photoreceptor.
The present invention also relates to a method of producing the
photoreceptor.
The present invention also relates to an image formation apparatus
comprising the photoreceptor, which is capable of producing high
quality images free of the light and shade stripes and streaks.
2. Discussion of Background
In recent years, there has been a strong demand for image formation
with high precision and high resolution in accordance with the
request for highly accurate reproduction of image information.
When image formation is carried out with high resolution, using a
photoconductor, in addition to an image to be formed based on an
original image information, an image based on the information of
the photoconductor itself is apt to be formed.
An image formation process by use of coherent light, such as laser
light, as writing light, is widely used in the field of
electrophotography for the formation of digital images, for
instance, as in copying machines, printers and facsimile apparatus.
In an electrophoto-graphic process using coherent light as writing
light, a problem is apt to be caused that an image including light
and shade stripes (hereinafter referred to as the light and shade
striped image) is formed due to the interference of the coherent
light within a photoconductive layer of the photoconductor.
It is known that such light and shade stripes are generated by the
writing light being intensified when the photoconductor satisfies
the relationship of 2nd=m.lambda. wherein n is the refractive index
of a charge transport layer, d is the thickness of the charge
transport layer, .lambda. is the wavelength of the writing light,
and m is an integer.
To be more specific, when .lambda.=780 nm and n=2.0, one set of
light and shade stripes appears at each change of 0.195 .mu.m in
the thickness of the charge transport layer. In order to remove the
light and shade stripes completely, it is necessary to reduce the
deviation of the thickness of the charge transport layer to less
than 0.195 .mu.m in the entire image formation area. However, it is
economically extremely difficult to produce a photoconductor with
such a small deviation of the thickness of the charge transport
layer as mentioned above, so that various methods have been
proposed to control or reduce the formation of the light and shade
stripes in the image.
For instance, in Japanese Laid-Open Patent Application 57-165645,
there is proposed a photoconductor comprising a support made of
aluminum, a charge transport layer formed on the support, a charge
generation layer comprising a-Si formed on the charge transport
layer, with the provision of a light absorption layer on the
aluminum support to remove the mirror reflection of the aluminum
support, thereby preventing the formation of the light and shade
stripes in images. The provision of the light absorption layer on
the aluminum support is extremely effective for preventing the
formation of the light and shade stripes in the image with the
photoconductor using the charge generation layer comprising a-Si
with the layer structure of the aluminum support/charge transport
layer/charge generation layer as mentioned above. However, for an
organic photoconductor with a layer structure of aluminum
support/charge generation layer layer/charge transport layer in
general use, the provision of the light absorption layer on the
aluminum support is not so effective for preventing the formation
of the light and shade stripes in the image.
In Japanese Laid-Open Patent Application 7-295269, there is
disclosed a photoconductor with a layer structure of aluminum
support/undercoat layer/charge generation layer/charge transport
layer, with the provision of a light absorption layer on the
aluminum support for preventing the formation of the light and
shade stripes in the image. However, the photoconductor with this
layer structure cannot completely prevent the formation of the
light and shade stripes in the image.
In Japanese Patent Publication 7-27262, there is disclosed an
electrophotographic copying apparatus comprising (1) a
photoconductor comprising a cylindrical support which has such a
convex cross section that is formed by superimposing a sub-peak on
a main peak, when the cylindrical support is cut by a plane which
includes the axis of the cylindrical support, and (2) an optical
system using a coherent light beam with a beam diameter which is
less than one period of the main peak for exposure. The support
disclosed in Japanese Patent Publication 7-27262 can be produced
relatively easily by machining or like.
In some photoconductors, the formation of the light and shade
stripes in the image can be controlled to some extent by use of the
above-mentioned support. However, many photoconductors cannot
prevent the formation of the light and shade stripes in the image
even though the above-mentioned support is used.
There is also known a photoconductor with the parameter of the
surface roughness of the support thereof being defined, for
example, in Japanese Laid-Open Patent Application 10-301311.
When an electrophotographic copying machine to be used with this
photoconductor adopts a low resolution, there is the case where the
formation of the light and shade striped image can be prevented.
However, when an electrophotographic copying machine with high
resolution is used, even if the surface roughness of the substrate
is defined by conventionally employed parameters such as maximum
height, ten-point mean roughness, and center-line mean roughness,
there cannot be determined the conditions under which the formation
of the light and shade striped image can be completely
prevented.
It is also generally known that the state of the formation of the
light and shade striped image can be changed by interposing an
undercoat layer comprising a white pigment such as titanium oxide
between the support and the photoconductive layer. However, the
necessary conditions for the undercoat layer to control the
formation of the light and shade striped image, such as the
thickness of the undercoat layer, largely differ depending upon the
surface state of the support, so that the conditions for completely
controlling the formation of the light and shade striped image have
not been determined.
Although the conditions for removing the light and shade stripes
entirely from the image are not completely known, there are many
cases where the formation of the light and shade striped image can
be reduced by roughening the surface of the support, so that a
photoconductor with the surface of the support being finely
roughened, produced by machining or like, is often mounted in an
image formation apparatus.
Furthermore, it is also known that the formation of the light and
shade striped image can be reduced by changing the thickness of the
undercoat layer, but its accurate conditions for reducing the
formation of the light and shade striped image are not completely
known, so that photoconductors are produced under various
conditions, and the conditions under which the light and shade
striped image is not formed when the photoconductor is mounted and
used in the electrophotographic copying machine are determined
experimentally. In order to produce a photoconductor which does not
form the light and shade striped image, the above experimentally
determined production conditions have to be strictly kept. Even
when such production conditions are strictly kept, there are many
cases where the light and shade stripes appear in the image when
the lot, the material and the shape of the photoconductor are
changed, so that it is necessary to check and change the production
conditions whenever the lot, the material and the shape of the
photoconductor are changed.
Even though there are the above-mentioned problems, as long as the
resolution of the image formation apparatus low, no big problems
occur. However, when an image formation apparatus capable of
producing images with high resolution is used, there is a case
where apart from the above-mentioned light and shade striped image,
an abnormal image including streaks (hereinafter referred to as the
streaked image) appears in the entire image. Such streaks are often
directed in the circumferential direction of the photoconductor
with almost the same intervals between the streaks. Unlike the
light and shade striped image, the streaked image appears, not only
at the place where the thickness of the photoconductive layer of
the photoconductor changes, but also in the area where the
thickness of the photoconductive layer is constant, so that the
abnormal streaked images often appear in the entire image area.
An investigation has been conducted as to the conditions under
which a photoconductor which produces such abnormal streaked images
is produced in the course of the continuous production of the
photoconductors. As a result, it has been found that the production
of such a photoconductor that produces the abnormal streaked images
relates to the timing of replacement of a cutting tool used for
machining the support of the photoconductor, and that there is a
tendency that at the time of replacement of the cutting tool, the
photoconductor that produces the abnormal streaked images is apt to
be produced. It has also been found that this tendency also depends
upon the kind of cutting tool employed. From the above, it can be
considered that the state of the surface of the support relates to
the production of the streaked images, but it is impossible to
define the state of the surface of the support for the
photoconductor which does not produce the streaked image by use of
the conventionally employed parameters relating to the surface
roughness.
For instance, in Japanese Laid-Open Patent Application 7-77817,
there is disclosed a method of producing the support for the
photoconductor by the steps of transforming a regular arrangement
of the surface state of the support to a sine wave function, and
transforming a regular arrangement of the lighting period of a
writing light to a sine wave function, synthesizing these two sine
wave functions to obtain a synthesized sine wave function,
determining the period of the synthesized sine wave function, and
controlling the machining of the support based on the thus
determined period of the synthesized sine wave function. More
specifically, in the method disclosed in Japanese Laid-Open Patent
Application 7-77817, the support is produced with the period of the
sine wave of the support set outside the scope of .+-.5% of the
period of the sine wave of the writing light. However, it is
extremely difficult to transform a profile of the support to a sine
wave, so that a new parameter is necessary to define a profile for
producing a photoconductor which does not produce streaked images
for use in the image formation apparatus capable of producing
images with high resolution.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide
a photoreceptor which does not produce abnormal images such as
light and shade striped images and streaked images, which are
formed by the multiple reflection of coherent light within the
photoreceptor.
A second object of the present invention is to provide a method of
evaluating the photoreceptor.
A third object of the present invention is to provide a method of
producing the photoreceptor.
A fourth object of the present invention is to provide an image
formation apparatus comprising the photoreceptor, which is capable
of producing high quality images free of the light and shade
stripes and the streaks.
The first object of the present invention can be achieved by a
photoreceptor comprising a support and a photosensitive layer
formed thereon, wherein when a group of data consisting of N
samples of the height x(t) (.mu.m) of a profile at the interface of
the photosensitive layer on the side of the support, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU1##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2):
##EQU2##
I(S) represented by formula (3): ##EQU3##
is calculated as being 6.0.times.10.sup.-3 or more.
In the present invention, when the photoreceptor is in the shape of
a drum as shown in FIG. 1(A), the horizontal direction of the
support indicates the direction along the support, which is in
parallel to the axis of the photoreceptor drum as indicated by the
arrow A as shown in FIG. 1(A), while when the photoreceptor is in
the shape of a rectangular sheet as shown in FIG. 1(B), the
horizontal direction of the support indicates the direction along
the plane of the support as indicated by the arrow B as shown in
FIG. 1(B).
The first object of the present invention can also be achieved by a
photoreceptor comprising a support and a photosensitive layer
formed thereon, wherein when a group of data consisting of N
samples of the height x(t) (.mu.m) of a profile at the interface of
the photosensitive layer on the side of the support, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU4##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula ##EQU5##
the relationship between the value of n.sub.max, at which
##EQU6##
is maximized in the range of n from 1 to N/2, and the pitch W.sub.l
(.mu.m) of writing light which is coherent light for image
formation is ##EQU7##
where m is an integer obtained by rounding off the decimals of
##EQU8##
provided that when ##EQU9##
The first object of the present invention can also be achieved by a
photoreceptor comprising a support, an undercoat layer formed on
the support, and a photosensitive layer formed on the undercoat
layer, wherein when a group of data consisting of N samples of the
height x(t) (.mu.m) of a profile of the surface of the undercoat
layer on the side of the photosensitive layer, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU10##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2):
##EQU11##
I(S) is calculated from formula (4): ##EQU12##
as being 6.0.times.10.sup.-3 or more.
The first object of the present invention can also be achieved by a
photoreceptor comprising a support, an undercoat layer formed on
the support, and a photosensitive layer formed on the undercoat
layer, wherein when a group of data consisting of N samples of the
height x(t) (.mu.m) of a profile at the surface of the undercoat
layer on the side of the photosensitive layer, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU13##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2),
##EQU14##
the relationship between the value of n.sub.max, at which
##EQU15##
is maximized in the range of n from 1 to N/2, and the pitch W.sub.l
(.mu.m) of writing light which is coherent light for image
formation is ##EQU16##
where m is an integer obtained by rounding off the decimals of
##EQU17##
provided that when ##EQU18##
The first object of the present invention can also be achieved by a
photoreceptor comprising a support and a photosensitive layer
formed thereon, wherein when a group of data consisting of N
samples of the height x(t) (.mu.m) of a profile of the surface of
the support on the side of the photosensitive layer, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU19##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula ##EQU20##
I(S) is calculated from formula (4): ##EQU21##
as being 12.0.times.10.sup.-3 or more.
The first object of the present invention can also be achieved by a
photoreceptor comprising a support and a photosensitive layer
formed on the support, wherein when a group of data consisting of N
samples of the height x(t) (.mu.m) of a profile of the surface of
the support on the side of the photosensitive layer, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to Fourier transformation in accordance with formula (1):
##EQU22##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2),
##EQU23##
the relationship between the value of n.sub.max, at which
##EQU24##
is maximized in the range of n from 1 to N/2, and the pitch W.sub.l
(.mu.m) of writing light which is coherent light for image
formation is ##EQU25##
where m is an integer obtained by rounding off the decimals of
##EQU26##
provided that when ##EQU27##
The second object of the present invention can be achieved by a
method of evaluating a photoreceptor comprising a support, an
undercoat layer formed on the support, and a photosensitive layer
formed thereon, comprising the steps of: subjecting a group of data
consisting of N samples of the height x(t) (.mu.m) of a profile at
the interface of the photosensitive layer on the side of the
support, and/or of a profile at the surface of the undercoat layer
on the side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU28## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU29## comparing a calculated power spectrum with a specific
reference, thereby evaluating the photoreceptor.
The second object of the present invention can also be achieved by
a method of evaluating a photoreceptor comprising a support and a
photosensitive layer formed thereon, comprising the steps of:
subjecting a group of data consisting of N samples of the height
x(t) (.mu.m) of a profile at the interface of the photosensitive
layer on the side of the support, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU30## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU31## calculating I(S) represented by formula (4) from the
calculated power spectrum, ##EQU32## comparing the calculated I(S)
with a specific reference, thereby evaluating the
photoreceptor.
The second object of the present invention can also be achieved by
a method of evaluating a photoreceptor comprising a support, an
undercoat layer formed on the support, and a photosensitive layer
formed thereon, comprising the steps of: subjecting a group of data
consisting of N samples of the height x(t) (.mu.m) of a profile at
the interface of the photosensitive layer on the side of the
support, and/or of a profile at the surface of the undercoat layer
on the side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU33## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU34## calculating I(S) represented by formula (4) from the
calculated power spectrum, ##EQU35## comparing the calculated I(S)
with a specific reference, thereby evaluating the
photoreceptor.
The second object of the present invention can also be achieved by
a method of evaluating a photoreceptor comprising a support and a
photosensitive layer formed thereon, comprising the steps of:
subjecting a group of data consisting of N samples of the height
x(t) (.mu.m) of a profile at the interface of the photosensitive
layer on the side of the support, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU36## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU37## calculating I'(S) represented by formula (5) from the
calculated power spectrum, ##EQU38## in which a and b each are an
integer of N or less, and a.ltoreq.b, and comparing the calculated
I'(S) with a specific reference, thereby evaluating the
photoreceptor.
The second object of the present invention can also be achieved by
a method of evaluating a photoreceptor comprising a support, an
undercoat layer formed on the support, and a photosensitive layer
formed thereon, comprising the steps of: subjecting a group of data
consisting of N samples of the height x(t) (.mu.m) of a profile at
the interface of the photosensitive layer on the side of the
support, and/or of a profile at the surface of the undercoat layer
on the side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU39## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU40## calculating I'(S) represented by formula (5) from the
calculated power spectrum, ##EQU41## in which a and b each are an
integer of N or less, and a.ltoreq.b, and comparing the calculated
I'(S) with a specific reference, thereby evaluating the
photoreceptor.
The third object of the present invention can be achieved by a
method of producing a photoreceptor comprising a support and a
photosensitive layer formed thereon, by determining the conditions
for machining the surface of the photosensitive layer on the side
of the support, and/or the surface of the support on the side of
the photosensitive layer in accordance with a method of evaluating
the photoreceptor, comprising the steps of: subjecting a group of
data consisting of N samples of the height x(t) (.mu.m) of a
profile at the interface of the photosensitive layer on the side of
the support, and/or of a profile at the surface of the support on
the side of the photoreceptor, measured perpendicular to the
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, to Fourier transformation in
accordance with formula (1): ##EQU42## wherein n and m are each an
integer, N=2.sup.p in which p is an integer, calculating a power
spectrum in accordance with formula (2): ##EQU43## and comparing a
calculated power spectrum with a specific reference, thereby
evaluating the photoreceptor.
The third object of the present invention can also be achieved by a
method of producing a photoreceptor comprising a support, an
undercoat layer formed on the support, and a photosensitive layer
formed on the undercoat layer, by determining the conditions for
machining the surface of the photosensitive layer on the side of
the support, and/or the surface of the undercoat layer on the side
of the photosensitive layer, and/or the surface of the support on
the side of the photosensitive layer in accordance with a method of
evaluating the photoreceptor, comprising the steps of: subjecting a
group of data consisting of N samples of the height x(t) (.mu.m) of
a profile at the interface of the photosensitive layer on the side
of the support, and/or of a profile at the surface of the undercoat
layer on the side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU44## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU45## and comparing a calculated power spectrum with a specific
reference, thereby evaluating the photoreceptor.
The third object of the present invention can also be achieved by a
method of producing a photoreceptor comprising a support and a
photosensitive layer formed thereon, by determining the conditions
for machining the surface of the photosensitive layer on the side
of the support, and/or the surface of the support on the side of
the photosensitive layer in accordance with a method of evaluating
the photoreceptor, comprising the steps of: subjecting a group of
data consisting of N samples of the height x(t) (.mu.m) of a
profile at the interface of the photosensitive layer on the side of
the support, and/or of a profile at the surface of the support on
the side of the photoreceptor, measured perpendicular to the
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, to Fourier transformation in
accordance with formula (1); ##EQU46## wherein n and m are each an
integer, N=2.sup.p in which p is an integer, calculating a power
spectrum in accordance with formula (2): ##EQU47## calculating I(S)
represented by formula (4) from the calculated power spectrum,
##EQU48## comparing the calculated I(S) with a specific reference,
thereby evaluating the photoreceptor.
The third object of the present invention can also be achieved by a
method of producing a photoreceptors comprising a support, an
undercoat layer formed on the support, and a photosensitive layer
formed on the undercoat layer, by determining the conditions for
machining the surface of the photosensitive layer on the side of
the support, and/or the surface of the undercoat layer on the side
of the photosensitive layer, and/or the surface of the support on
the side of the photosensitive layer in accordance with a method of
evaluating the photoreceptor, comprising the steps of: subjecting a
group of data consisting of N samples of the height x(t) (.mu.m) of
a profile at the interface of the photosensitive layer on the side
of the support, and/or of a profile at the surface of the undercoat
layer on the side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU49## wherein n
and m are each an integer, N=2.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2):
##EQU50## calculating I(S) represented by formula (4) from the
calculated power spectrum, ##EQU51## and comparing the calculated
I(S) with a specific reference, thereby evaluating the
photoreceptor.
The third object of the present invention can also be achieved by a
method of producing a photoreceptor comprising a support and a
photosensitive layer formed thereon, by determining the conditions
for machining the surface of the photosensitive layer on the side
of the support, and/or the surface of the support on the side of
the photosensitive layer in accordance with a method of evaluating
the photoreceptor, comprising the steps of: subjecting a group of
data consisting of N samples of the height x(t) (.mu.m) of a
profile at the interface of the photosensitive layer on the side of
the support, and/or of a profile at the surface of the support on
the side of the photoreceptor, measured perpendicular to the
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, to Fourier transformation in
accordance with formula (1): ##EQU52## wherein n and m are each an
integer, N=2.sup.p in which p is an integer, calculating a power
spectrum in accordance with formula (2): ##EQU53## calculating
I'(S) represented by formula (5) from the calculated power
spectrum, ##EQU54## in which a and b each are an integer of N or
less, and a.ltoreq.b, and comparing the calculated I'(S) with a
specific reference, thereby evaluating the photoreceptor. The third
object of the present invention can also be achieved by a method of
producing a photoreceptor comprising a support, an undercoat layer
formed on the support, and a photosensitive layer formed on the
undercoat layer, by determining the conditions for machining the
surface of the photosensitive layer on the side of the support,
and/or the surface of the undercoat layer on the side of the
photosensitive layer, and/or the surface of the support on the side
of the photosensitive layer in accordance with a method of
evaluating the photoreceptor, comprising the steps of: subjecting a
group of data consisting of N samples of the height x(t) (.mu.m) of
a profile at the interface of the photosensitive layer on the side
of the support, and/or of a profile at the surface of the undercoat
layer on the.side of the photoreceptor, and/or of a profile at the
surface of the support on the side of the photoreceptor, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, to Fourier
transformation in accordance with formula (1): ##EQU55## wherein n
and m are each an integer, N=21.sup.p in which p is an integer,
calculating a power spectrum in accordance with formula (2);
##EQU56## calculating I'(S) represented by formula (5) from the
calculated power spectrum, ##EQU57## in which a and b each are an
integer of N or less, and a.ltoreq.b, and comparing the calculated
I'(S) with a specific reference, thereby evaluating the
photoreceptor.
The fourth object of the present invention can be achieved by an
image formation apparatus comprising a photoreceptor which
comprises a support and a photosensitive layer formed thereon,
wherein when a group of data consisting of N samples of the height
x(t) (.mu.m) of a profile at the interface of the photosensitive
layer on the side of the support, measured perpendicular to the
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, is subjected to Fourier
transformation in accordance with formula (1): ##EQU58##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula ##EQU59##
I(S) represented by formula (3): ##EQU60##
is calculated as being 6.0.times.10.sup.-3 or more, in which
coherent light is used as writing light for image formation.
The fourth object of the present invention can also be achieved by
an image formation apparatus comprising a photoreceptor which
comprises a support, an undercoat layer formed on the support, and
a photosensitive layer formed on the undercoat layer, wherein when
a group of data consisting of N samples of the height x(t) (.mu.m)
of a profile of the surface of the undercoat layer on the side of
the photosensitive layer, measured perpendicular to the horizontal
direction of the support, taken at .DELTA.t (.mu.m) intervals in
the horizontal direction, is subjected to Fourier transformation in
accordance with formula (1): ##EQU61##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2):
##EQU62##
I(S) is calculated from formula (4): ##EQU63##
as being 6.0.times.10.sup.-3 or more, in which coherent light is
used as writing light for image formation.
The fourth object of the present invention can also be achieved by
an image formation apparatus comprising a photoreceptor which
comprises a support and a photosensitive layer formed thereon,
wherein when a group of data consisting of N samples of the height
x(t) (.mu.m) of a profile of the surface of the support on the side
of the photosensitive layer, measured perpendicular to the
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, is subjected to Fourier
transformation in accordance with formula (1): ##EQU64##
wherein n and m are each an integer, N=2.sup.p in which p is an
integer, in a power spectrum represented by formula (2):
##EQU65##
I(S) is calculated from formula (4): ##EQU66##
as being 12.0.times.10.sup.-3 or more, in which coherent light is
used as writing light for image formation.
BRIEF DESCRIPTION OF TEE DRAWINGS
A more complete appreciation of the invention and many of the
attendant advantages thereof will be readily obtained as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings, wherein:
FIGS. 1(A) and 1(B) respectively show a drum-shaped photoreceptor
and a sheet-shaped photoreceptor of the present invention,
indicating the horizontal direction of the support for each of the
photoreceptors.
FIG. 2 shows a profile of the outer surface of an aluminum drum A
which was cut with a cutting machine equipped with a brand-new
diamond cutting tool.
FIG. 3 shows a profile of the outer surface of an aluminum drum B
which was cut with the same cutting machine as mentioned above
after 500 aluminum drums were cut.
FIG. 4 shows a power spectrum of the outer surface of the aluminum
drum A (.DELTA.t=0.31 .mu.m, N=4096).
FIG. 5 shows a power spectrum of the outer surface of the aluminum
drum B (.DELTA.t=0.31 .mu.m, N=4096).
FIG. 6 shows a profile of the outer surface of the aluminum drum
used in Example 1.
FIG. 7 is a power spectrum of the outer surface of the aluminum
drum used in Example 1.
FIG. 8 is a profile of the surface of the undercoat layer of the
photoreceptor in Example 1.
FIG. 9 is a power spectrum of the surface of the undercoat layer of
the photoreceptor in Example 1.
FIG. 10 is a profile of the surface of the undercoat layer of the
photoreceptor in Example 2.
FIG. 11 is a power spectrum of the surface of the undercoat layer
of the photoreceptor in Example 2.
FIG. 12 is a profile of the outer surface of the aluminum drum in
Comparative Example 1.
FIG. 13 is a power spectrum of the outer surface of the aluminum
drum in Comparative Example 1.
FIG. 14 is a profile of the outer surface of the aluminum drum in
Example 14.
FIG. 15 is a power spectrum of the outer surface of the aluminum
drum in Example 14.
FIG. 16 is a profile of the outer surface of the aluminum drum in
Comparative Example 8.
FIG. 17 is a power spectrum of the outer surface of the aluminum
drum in Comparative Example 8.
FIG. 18 is a profile of the outer surface of the aluminum drum in
Example 24.
FIG. 19 is a power spectrum of the outer surface of the aluminum
drum in Example 24.
FIG. 20 is a profile of the surface of the undercoat layer of the
photoreceptor in Example 24.
FIG. 21 is a power spectrum of the surface of the undercoat layer
of the photoreceptor in Example 24.
FIG. 22 is a power spectrum of the outer surface of the aluminum
drum in Comparative Example 11.
FIG. 23 is a profile of the outer surface of a 85th machined
aluminum drum in Example 28.
FIGS. 24 and 25 are a power spectrum of the outer surface of the
aluminum drum in Example 28.
FIG. 26 is a profile of the surface of the undercoat layer of the
photoreceptor in Example 28.
FIGS. 27 and 28 are a power spectrum of the surface of the
undercoat layer of the photoreceptor in Example 28.
FIG. 29 a profile of the outer surface of the aluminum drum in
Example 32.
FIG. 30 is a power spectrum of the outer surface of the aluminum
drum in Example 32.
DESCRIPTION OF TH PREFERRED EMBODIMENTS
The inventors of the present invention have conducted
investigations as to why some photoreceptors for use in
electrophotographic copying machine produce the light and shade
striped images, which might be considered to be caused by the
multiple reflection of writing light within the photoreceptor, and
other photoreceptors do not produce such light and shade striped
images. As a result, they have discovered that the formation of the
light and shade striped images correlate to the state of the
surface of the photosensitive layer on the side of the support at
the interface between the photosensitive layer and the support.
However, there is a case where even though one photoreceptor
produces the light and shade striped image, while other
photoreceptor does not produce the light and shade striped image,
there are almost no differences between the two photoreceptors in
such surface roughness parameters as measured by the Japanese
Industrial Standards, maximum height, ten-point mean roughness, and
center-line mean roughness, with respect to the interface of the
photosensitive layer on the side of the support.
Furthermore, there is even a case where the tendency of the
formation of the light and shade striped image is reversed with
respect to the above-mentioned surface roughness parameters.
It is considered that the interface of the photosensitive layer on
the side of the support could be effectively controlled by
controlling the state of the surface of the support. However, a
preferable state of the surface of the support cannot be defined by
use of the conventional surface roughness parameters.
Furthermore, even though the same photoreceptor is used in
different image formation apparatus, the state of the formation of
the light and shade striped image differs depending upon the image
formation apparatus employed, and is largely changed in accordance
with the spot diameter of writing light employed. However, it has
not been clarified what factors cause such differences in the
formation of the light and shade striped image.
The inventors of the present invention have studied the mechanism
of the formation of the light and shade striped image and tried to
control the interface of the photosensitive layer on the side of
the support in order to provide a photoreceptor which is free of
the problem of forming the light and shade striped image. Further,
the study has been conducted from the view point that even if the
light and shade striped image is formed, as long as the intervals
between the stripes are too small to recognize visually, the
formation of such light and shade striped image will cause no
problem.
According to the present invention, it has been discovered that the
interface of the photosensitive layer on the side of the support
has minute unevenness in the form of a number of waves, and that by
forming an appropriate unevenness at the interface of the
photosensitive layer on the side of the support so as to increase
the power of all the waves of the unevenness, the formation of the
light and shade stripes can be made invisible to the naked eye.
That the waves have a large power means that the interface of the
photoreceptor on the side of the support has sufficiently large
roughness in its entirety or sufficiently roughened, so that the
intervals between the flight and shade stripes are too narrow to
visually recognize the light and shade stripes.
The photoreceptor of the present invention comprises a support and
a photosensitive layer formed thereon comprising at least a charge
generation material and a charge transport material, optionally
with the provision of an undercoat layer and a protective
layer.
The photoreceptor of the present invention may be either (1) a
layered photoreceptor comprising a charge generation layer
comprising a charge generation material and a charge transport
layer comprising a charge transport material, which layers are
overlaid one on another, or (2) a single layer photoreceptor
comprising a photosensitive layer comprising a charge generation
material and a charge transport material in the form of a mixture.
Both the layered photoreceptor and the single layer photoreceptor
of the present invention exhibit excellent photographic
characteristics. The profile of the interface of the photosensitive
layer on the side of the support can be represented by the profile
of the overlaid photosensitive layer or of the support as long as
the layer of the photosensitive layer on the side of the support or
the support itself is not dissolved or deformed by the formation of
the photosensitive layer.
When the photoreceptor has an undercoat layer, a profile of the
surface of the undercoat layer can be used for the above-mentioned
profile.
When the photoreceptor does not have the undercoat layer, a profile
of the surface of the support can be used for the above-mentioned
profile.
As a method for measuring the profile in the present invention, an
optical method, an electrical method, an electrochemical method,
and a physical method can be employed. Any method can be employed
as long as the method has excellent reproducibility and high
measurement accuracy and is simple to use. Of the above-mentioned
methods, an optical method and a physical method are preferable
since such methods are simple to use. A physical method using a
feeler is considered to be most preferable since it has excellent
reproducibility and measurement accuracy.
The power of the wave of the interface of the photosensitive layer
on the side of the support can be represented by I(S) which is
calculated by the steps of (1) subjecting a group of data to
discrete Fourier transformation, which group of data consists of N
samples of the height x(t) (.mu.m) of the profile of the
photoreceptor measured perpendicular to the horizontal direction of
the photoreceptor taken at .DELTA.t (.mu.m) intervals, in
accordance with the following formula: ##EQU67##
wherein n and m are an integer, N=2.sup.p in which p is an integer,
(2) obtaining a power spectrum represented by the following
formula: ##EQU68##
and (3) calculating from the power spectrum I(S) represented by the
following formula: ##EQU69##
The value of I(S) is 6.0.times.10.sup.-3 or more, preferably
8.0.times.10.sup.-3 or more, more preferably 10.0.times.10.sup.-3
or more, furthermore preferably 12.0.times.10.sup.-3 or more.
When the value of I(S) is less than 6.0.times.10.sup.-3, the power
of the wave of the interface of the photosensitive layer on the
side of the support is so weak in its entirety that the portions
where the intervals of the light and shade stripes are broad are
apt to exist, and the problem of the light and shade striped image
likely occurs. In order to control or reduce only the formation of
the light and shade striped image, the larger the value of I(S),
the better. However, when the value of I(S) is excessively large,
short circuit tends to be caused by a burr of the support, or a
photoconductive material tends to coagulate around the burr, and
discharge destruction of the photosensitive layer tends to occur,
so that apart from the light and shade striped image, further
abnormal images are apt to be formed. Therefore, it is preferable
that the value of I(S) be approximately 100.0.times.10.sup.-3 or
less, although it depends upon the image formation apparatus
employed.
When the horizontal direction of the profile of the interface of
the photosensitive layer on the side of the support is t[.mu.m],
the surface roughness x(t)[.mu.m] of the interface of the
photoreceptor irregularly varies, the amount of which is here
referred to as an irregular variate. Any variate can be obtained by
Fourier transformation by synthesizing sine wave variations with
various frequencies, using an appropriate phase and an amplitude.
##EQU70##
wherein k is the wave number [.mu.m.sup.-1 ; the number of waves
per .mu.m]. The Fourier component X(k) represents the amplitude of
the wave with the wave number k, namely, with a wavelength of
.lambda.(=1/k [.mu.m]), which is contained in the irregular
variate. .vertline.X(k).vertline..sup.2 represents the energy of
the component wave with the wave number k.
The distribution relationship between the wave number k and the
energy .vertline.X(k).vertline..sup.2 of the component wave, that
is, the spectrum, will now be considered. ##EQU71##
S(k) is an average energy of the component wave with the wave
number k of the profile per unit interval [1 .mu.m], and is defined
as the power spectrum. However, the height x(t) of the profile
cannot be practically defined in the range of
-.infin.<t<.infin.. The measurement thereof is carried out
within part of the profile, -T/2.ltoreq.t.ltoreq.T/2, so that in
calculating S(k), such a limit of T as T.fwdarw..infin. is not
used, but there is used such a value for T that an average value
thereof is sufficiently large relative to the wavelength 1/k as a
macroscopic physical amount, whereby ##EQU72##
is calculated. Practically, the result is identical when the limit
of T.fwdarw..infin. is used.
The Fourier transformation is changed to the following due to the
use of discrete Fourier transformation: ##EQU73##
wherein n and m are an integer, N is the number of sampling points
for measurement of the surface roughness, which is required to be
an integer represented by N=2.sup.p, and .DELTA.t[.mu.m] is the
intervals of the sampling points for the measurement of the height
of the profile, and is in the relationship of T/.DELTA.t=N.
When the range T for the measurement of the profile in the
horizontal direction is too short, the number of waves for the
transformation becomes too small, so that a measurement error is
increased and the existing waves cannot be evaluated. It is
necessary to select an appropriate value for the measurement range
T in accordance with the values of .DELTA.t and N.
In the photoreceptor of the present invention, the measurement
range T is approximately in the range of 500 nm to 5000 .mu.m,
preferably in the range of 600 nm to 4000 .mu.m, more preferably in
the range of 700 nm to 3000 .mu.m, except when it is necessary to
take into consideration a wave with an extremely long wavelength
such as surface waviness.
The inventors of the present invention have determined and studied
the power spectrum with respect to each combination of the number N
of the sampling points at the interface of the photosensitive layer
on the side of the support of the photoreceptor of the present
invention and the value of .DELTA.t. The result was that it was
confirmed that the power spectrum sufficiently converges when the
sampling interval .DELTA.t was 0.31 [.mu.m] (.DELTA.t=0.31 [.mu.m])
and N was 4096 (N=4096) as indicated in working examples of the
present invention.
The power spectrum was derived by a discrete Fourier transformation
by the following calculation: ##EQU74##
I(S) was calculated by use of the following formula: ##EQU75##
wherein n and m are an integer, N=2.sup.p in which p is an
integer.
It was also confirmed that when .DELTA.t=0.31 [.mu.m], the integral
value converged within several % of error at N=4096.
From a different angle, the above can be considered as follows:
When the sampling interval (real space) of the measurement of the
roughness of the interface of the photosensitive layer on the side
of the support is .DELTA.t[.mu.m], the sampling interval
(reciprocal space) of the power spectrum is
.DELTA.n=1/(N.multidot..DELTA.t) [.mu.m.sup.-1 ]. This is because
the domain of definition of the height x(t) of the profile is the
interval of T-N.multidot..DELTA.t. This indicates that the original
signal x(t) can be reproduced by the Fourier spectrum of the value
of the sample with the interval of .DELTA.n
(=1/(N.multidot..DELTA.t)) in the reciprocal space. The variation
period of the profile that can be reproduced here is approximately
2.DELTA.t in accordance with Shannon's sampling theorem.
With respect to the phenomenon now in consideration, a surface
roughness with a variation period above the above-mentioned
variation period is involved, so that the sampling interval of
.DELTA.t (=0.31 [.mu.m]) is sufficient. It may be necessary to
consider a more minute variation period in case a different
phenomenon takes place. In such a case, the sampling interval is
further shortened in accordance with the variation period.
In order to control the I(S) of the profile of the photosensitive
layer on the side of the support, it is extremely effective to
control the profile of the surface of the support. This is so when
the photoreceptor includes no undercoat layer. Even when the
photoreceptor includes an undercoat layer which is provided on the
support, with the photosensitive layer being overlaid on the
undercoat layer, as long as the undercoat layer is not extremely
thick, the unevenness of the surface of the support faithfully
reflects on the surface of the undercoat layer, so that it is
easier and much more effective to control the I(S) of the profile
of the photosensitive layer on the side of the support by
controlling the profile of the surface of the support than by
controlling the composition of the undercoat layer and the method
of overlaying the undercoat layer on the support.
The I(S) of the profile of the surface of the support, which is
measured in the same manner as that of the profile of the
photosensitive layer on the side of the support, is preferably
12.0.times.10.sup.-3 or more, more preferably 14.0.times.10.sup.-3
or more, furthermore preferably 16.0.times.10.sup.-3 or more.
When the value of I(S) is less than 12.0.times.10.sup.-3, in
particular in the photoreceptor provided with the undercoat layer,
the power of the wave of the interface of the photosensitive layer
on the side of the support is so weak in its entirety that the
portions where the intervals of the light and shade stripes are
broad are apt to exist, and the problem of the light and shade
striped image likely occurs. In order to control or reduce only the
formation of the light and shade striped image, the larger the
value of I(S) of the profile of the surface of the support, the
better. However, when the value of I(S) is excessively large, short
circuit tends to be caused by a burr of the support, or a
photo-conductive material tends to coagulate around the burr, and
discharge destruction of the photosensitive layer tends to occur,
so that apart from the light and shade striped image, further
abnormal images are apt to be formed as mentioned above. Therefore,
it is preferable that the value of I(S) be approximately
150.0.times.10.sup.-3 or less, although it depends upon the image
formation apparatus employed.
The inventors of the present invention have discovered that in the
photoreceptor comprising the support, the undercoat layer provided
on the support, and the photosensitive layer overlaid on the
undercoat layer, the relationship between the state of the surface
of the support and the spot diameter of writing light has some
connection with the formation of the light and shade striped
image.
As mentioned above, the support for the photoreceptor has minute
unevenness or roughness at the surface thereof and the minute
unevenness is composed of a number of waves. The inventors of the
present invention have discovered that of such waves, the waves
with a wavelength which is 1/2 or more of the spot diameter of
writing light are involved in the formation of the light and shade
striped image.
That the waves having a wavelength which is 1/2 or more of the spot
diameter of the writing light have high energy in the entirety
thereof means that the surface of the photoreceptor largely varies
by the wave having a wavelength which is 1/2 or more of the spot
diameter of the writing light. The reasons why, of the waves which
constitute the surface of the photoreceptor, the waves having a
wavelength which is 1/2 or more of the spot diameter of the writing
light are involved in the formation of the light and shade striped
image, and the waves having a wavelength which is less than 1/2 of
the spot diameter of the writing light are not involved in the
formation of the light and shade striped image, have not yet
clarified, but there is clearly a correlation between the
wavelength and the formation of the light and shade striped image
as mentioned above. Thus, it is considered that some optical
effects in the course of the writing process by the writing light
work on the formation of the light and shade striped image.
Therefore, of the waves that constitute the profile of the support
for the photoreceptor, the I(S) of the waves with a wavelength of
.phi./2 (.mu.m) or more is important, where .phi. (.mu.m) is the
spot diameter of the writing light.
The profile of the surface of the support for the photoreceptor of
the present invention is subjected to discrete Fourier
transformation with respect to a group of data which consists of N
samples of the height x(t) (.mu.m) of the profile in the horizontal
direction of the photoreceptor taken at .DELTA.t (.mu.m) intervals,
in accordance with the following formula: ##EQU76##
wherein n and m are an integer, N=2.sup.p in which p is an
integer.
The value of I'(S) of the wave with a wavelength of .phi./2 or
more, derived from the following formula, is 6.0.times.10.sup.-3 or
more, preferably 8.0.times.10.sup.-3 or more, more preferably
9.0.times.10.sup.-3 or more: ##EQU77##
wherein j is a maximum integer which satisfies
N.multidot..DELTA.t/j.gtoreq..phi./2, and .phi. is the spot
diameter (.mu.m) of writing light for image formation.
The inventors of the present invention next studied how different
the photoreceptor that produces various streaked images and the
photoreceptor that does not produce the streaked images are. As a
result, the inventors of the present invention discovered that in
the photoreceptor that produces the streaked images, the potential
of the latent image on the photoreceptor varies at almost equal
intervals in the long axial direction of the photoreceptor, and
considered that the variations in the potential may be larger in
the photoreceptor that produces the streaked images than in the
photoreceptor that does not produce the streaked images. In order
to back up this consideration, the inventors of the present
invention closely observed the photoreceptors and discovered that
in the photoreceptor that produces the streaked images, the
photosensitivity varies at substantially the same intervals as the
intervals of the streaks of the streaked images in the long axial
direction of the photoreceptor, and that the intervals of the
variation are almost the same as those of the unevenness of the
interface of the photosensitive layer on the side of the support,
while in the photoreceptor that does not produce the streaked
images, there is the same unevenness at the interface thereof on
the side of the support as in the photoreceptor that produces the
streaked images, the unevenness is less irregular in shape than the
unevenness in the photoreceptor that produces the streaked
images.
In the photoreceptor with extremely reduced irregularities in the
unevenness at the interface thereof on the side of the support, a
large unevenness itself is generally difficult to find at the
interface, so that the interface is nearly smooth and therefore the
photoreceptor does not produce the streaked images, but tends to
produce grained light and dark striped images or band-shaped light
and dark striped images. This tendency is particularly conspicuous
when an undercoat layer is used.
As mentioned above, the surface of the support for the
photoreceptor usually often has unevenness or roughness which is
formed by the machining or other working of the support. In the
case where the support for the photoreceptor is cylindrical, the
support is usually machined and worked on a lathe as the support is
rotated, using a cutting tool as it is moved, and an unevenness
with a relatively large amplitude is formed on the surface of the
support at intervals equal to the moving speed of the cutting tool.
The intervals of concave portions and convex portions in the
unevenness with the relatively large amplitude often have such a
period that corresponds to about 1/2 to 1/3 to several times the
period of the writing light used in the image formation apparatus
employed.
When a charge generation layer is provided on this support, with
the application of a coating liquid for the formation of the charge
generation layer to the support, by the immersion coating method,
the coating liquid is apt to move more into concave portions than
into convex portions of the support, so that the deposition amount
of the charge generation layer tends to change so as to reflect the
unevenness of the surface of the support. Therefore, the variation
in the photosensitivity of the photoreceptor tends to have such a
regularity so as to reflect the unevenness of the surface of the
support. It is considered that when the period of the variation is
increased to about one or more integer times the period of the
period of the writing light, the picture elements formed by the
irradiation of the writing light have a light and shade period,
whereby streaked images are formed. Even if the charge generation
layer is uniformly deposited when it is overlaid on the support,
since the surface of the photoreceptor is generally microscopically
flat, so that the thickness of the charge transport layer
microscopically varies in accordance with the unevenness of the
support. It is considered therefor that when the support has some
regularity in the unevenness of the surface thereof, the way of the
multiple reflection of the writing light within the charge
transport layer comes to have a regularity, so that the apparent
photosensitivity of the photoreceptor comes to have a regularity,
and when the period of the variation of the photosensitivity
amounts to about one or more integer times the period of the
writing light, the picture elements formed come to have a light and
shade periodicity, whereby streaked images are formed.
More specifically, it has been discovered that the photoreceptor
comprising at least the photosensitive layer on the support having
the following features is capable of controlling the formation of
the streaked images:
In the profile of the interface of the photosensitive layer on the
side of the support for the photoreceptor, when a group of data
which consists of N samples of the height x(t) (.mu.m) of the
profile, measured perpendicular to a horizontal direction of the
support, taken at .DELTA.t (.mu.m) intervals in the horizontal
direction, is subjected to discrete Fourier transformation in
accordance with the following formula: ##EQU78##
wherein n and m are an integer, N=2.sup.p in which p is an integer,
a power spectrum derived from the following formula, ##EQU79##
has a plurality of peaks in a region in which n satisfies
##EQU80##
In such a photoreceptor as mentioned above, the microscopic
variations in the thickness of the photosensitive layer can be made
sufficiently fine and irregular, so that any regularity can be
removed in the way of the multiple reflection of the writing light
within the charge transport layer, and therefore the streaked
images are practically-not formed.
The wave with a wavelength of about 5 .mu.m or less, in which n is
in the region of ##EQU81##
has too small an amplitude to have a substantial effect of
controlling the regularity of the microscopic variations in the
thickness of the photosensitive layer.
On the other hand, the wave with a wavelength of about 50 .mu.m or
more, in which n is in the region of ##EQU82##
has little effect of making sufficiently minutely irregular the
microscopic variations in the thickness of the photosensitive layer
because of the long wavelength.
The magnitude of the plurality of the peaks which is present in the
region in which n satisfies ##EQU83##
is extremely important for controlling the regularity of the
microscopic variations in the thickness of the photosensitive
layer.
The magnitude of the peaks, ##EQU84##
is ##EQU85##
preferably ##EQU86##
more preferably ##EQU87##
When the magnitude of the peaks is ##EQU88##
the power of the wave is so small that the effect of making
sufficiently minutely irregular the microscopic variations in the
thickness of the photosensitive layer cannot be controlled.
Furthermore, the deposition amount of the charge generation layer
tends to have a periodicity and therefore the peak with the
magnitude cannot be such a peak that controls the formation of the
streaked images. The number of the peaks is plural, preferably 4 or
more, more preferably 7 or more.
That there is a plurality of the peaks means that there is a
plurality of waves, each having a different wavelength, and the
microscopic variations in the thickness of the photosensitive layer
can be made sufficiently minutely irregular to such a degree that
corresponds to the number of the peaks. Thus, the streaked images
are hardly visually recognized to the naked eye. In contrast to
this, when there is only one peak, the microscopic variations in
the thickness of the photosensitive layer come to have regularity,
which may often disadvantageously cause the formation of abnormal
images.
When the photosensitive layer is provided on the support through
the undercoat layer, it is particularly effective to form minute
unevenness on the surface of the undercoat layer. This is because
as long as the undercoat layer is neither dissolved or swollen when
the photosensitive layer is overlaid thereon, the state of the
surface of the undercoat layer becomes almost the same as that of
the interface of the photosensitive layer on the side of the
support, so that by forming the minute unevenness on the surface of
the undercoat layer, the minute unevenness can be easily formed at
the interface of the photosensitive layer on the side of the
support.
More specifically, it has been discovered that the photoreceptor
comprising at least the photosensitive layer on the support having
the following features is capable of controlling the formation of
streaked images: when a group of data which consists of N samples
of the height x(t) (.mu.m) of the profile of the interface of the
undercoat layer, measured perpendicular to a horizontal direction
of the support, taken at .DELTA.t (.mu.m) intervals in the
horizontal direction, is subjected to discrete courier
transformation in accordance with the following formula:
##EQU89##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, a power spectrum derived from the following formula,
##EQU90##
has a plurality of peaks in a region in which n satisfies
##EQU91##
The wave with a wavelength of about 5 .mu.m or less, in which n is
in the region of ##EQU92##
has too small an amplitude to have a substantial effect of
controlling the movement of the coating liquid for the formation of
the photosensitive layer at the time of drying thereof. The
wavelength is also too short to sufficiently make irregular the
variations in the unevenness of the photosensitive layer at the
interface on the side of the support.
On the other hand, a wave with a wavelength of about 50 .mu.m or
more, in which n is in the region of ##EQU93##
tends to bring about the movement of the coating liquid for the
formation of the photosensitive layer at the time of drying
thereof.
The magnitude of the plurality of the peaks which is present in the
region in which n satisfies ##EQU94##
is extremely important for controlling the movement of the coating
liquid for the formation of the photosensitive layer at the time of
drying thereof.
The magnitude of the peaks ##EQU95##
is ##EQU96##
preferably ##EQU97##
more preferably ##EQU98##
When the magnitude of the peaks is ##EQU99##
the power of the wave is so small that the movement of the coating
liquid cannot be controlled and therefore streaked images are apt
to be formed, and this range is not preferable.
The number of the peaks is plural, preferably 4 or more, more
preferably 7 or more.
That there is a plurality of the peaks means that there is a
plurality of waves, each having a different wavelength, and the
movement of the coating liquid at the time of the drying thereof is
controlled differently by each wave, causing irregular movement of
the coating liquid, so that even if streaked images are formed,
such images are eventually made irregular in appearance and almost
cannot be recognized by the naked eye.
In contrast to this, when there is only one peak, the movement of
the coating liquid is controlled regularly, which may often
disadvantageously cause the formation of abnormal images.
Furthermore, when there is only one peak, the power of the wave
itself tends to become so weak that the effect of controlling the
movement of the coating liquid is disadvantageously small.
It is extremely important that the above-mentioned unevenness is
formed on the surface of the support for the photoreceptor. This is
because when the undercoat layer is not provided on the support, as
long as the photosensitive layer is neither dissolved or swollen
when the photosensitive layer is provided, the state of the
interface of the photosensitive layer on the side of the support is
substantially the same as the state of the surface of the support,
and when the undercoat layer is provided on the support, in
particular, when the undercoat layer is provided by coating a
coating liquid for the formation of the undercoat layer on the
support, the unevenness formed on the surface of the support works
to control the movement of the coating liquid on the surface of the
support, so that the unevenness has an effect of making it
difficult to reflect regular waves with a large amplitude on the
interface of the photosensitive layer on the side of the
support.
More specifically, it has been discovered that the photoreceptor
comprising at least the photosensitive layer on the support having
the following features is capable of controlling the formation of
streaked images extremely effectively: when a group of data which
consists of N samples of the height x(t) (.mu.m) of the profile of
the interface of the support, measured perpendicular to a
horizontal direction of the support, taken at .DELTA.t (.mu.m)
intervals in the horizontal direction, is subjected to discrete
Fourier transformation in accordance with the following formula:
##EQU100##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, a power spectrum derived from the following formula,
##EQU101##
has a plurality of peaks in a region in which n satisfies
##EQU102##
The wave with a wavelength of about 5 .mu.m or less, in n which n
is in the region of ##EQU103##
has too small an amplitude to have a substantial effect of
controlling the movement of the coating liquid for the formation of
the undercoat layer or the photosensitive layer at the time of
drying thereof.
On the other hand, a wave with a wavelength of about 50 .mu.m or
more, in which n is in the region of ##EQU104##
tends to bring about the movement of the coating liquid for the
formation of the photosensitive layer at the time of drying
thereof.
The magnitude of the plurality of the peaks which is present in the
region in which n of the power spectrum of the profile of the
undercoat layer satisfies ##EQU105##
extremely important for controlling the movement of the coating
liquid for the formation of the undercoat layer or the
photosensitive layer at the time of drying thereof.
The magnitude of the peaks, ##EQU106##
is ##EQU107##
preferably ##EQU108##
more preferably ##EQU109##
When the magnitude of the peaks is ##EQU110##
the power of the wave is so small that the movement of the coating
liquid cannot be controlled and therefore streaked images are
disadvantageously apt to be formed, and this range is not
preferable.
The number of the peaks is plural, preferably 4 or more, more
preferably 7 or more.
That there is a plurality of the peaks means that there is a
plurality of waves, each having a different wavelength, and the
movement of the coating liquid at the time of the drying thereof is
controlled differently by each wave, causing irregular movement of
the coating liquid, so that even if streaked images are formed,
such images are eventually made irregular in appearance and almost
cannot be recognized by the naked eye.
In contrast to this, when there is only one peak, regularity is
caused in the movement of the coating liquid at the time of drying
the coating liquid, which regularity may often disadvantageously
lead to the formation of abnormal images. Furthermore, when there
is only one peak, the power of the wave itself tends to become so
weak that the effect of controlling the movement of the coating
liquid is disadvantageously small.
As long as the support for the photoreceptor is prepared by
machining as mentioned above, there cannot be avoided the formation
of the unevenness with a wavelength of about 1/3 to 3 times the
period of the writing light at the interface of the photosensitive
layer of the photoreceptor on the side of the support. In order to
cancel the periodicity of the unevenness and to control the
formation of the streaked image, it is effective to form the
unevenness with a plurality of wavelengths on the surface of the
support.
More specifically, in the photoreceptor comprising at least the
photosensitive layer on the support, a photoreceptor having the
following features is capable of reducing the formation of streaked
images extremely effectively: when a group of data which consists
of N samples of the height x(t) (.mu.m) of the profile of the
interface of the photosensitive layer on the side of the support,
measured perpendicular to the horizontal direction of the support,
taken at .DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to discrete Fourier transformation in accordance with the
following formula: ##EQU111##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, a power spectrum derived from the following formula,
##EQU112##
has a plurality of peaks in a region in which n satisfies
##EQU113##
In this case, the peak value of the power spectrum is extremely
important. It is preferable that in the region where n satisfies
##EQU114##
the power spectrum have a plurality of peaks that satisfies the
conditions of ##EQU115##
more preferably ##EQU116##
furthermore preferably ##EQU117##
When ##EQU118##
the power of the wave is so weak that the effect of controlling the
regularity of the unevenness at the interface of the photosensitive
layer on the side of the support is small and therefore the
streaked images are apt to be formed.
In the photoreceptor comprising the photosensitive layer which is
provided via an undercoat layer on the support, a photoreceptor
having the following features is also capable of reducing the
formation of streaked images extremely effectively: when a group of
data which consists of N samples of the height x(t) (.mu.m) of the
profile of the undercoat layer at the interface of the
photosensitive layer, measured perpendicular to the horizontal
direction of the support, taken at .DELTA.t (.mu.m) intervals in
the horizontal direction, is subjected to discrete Fourier
transformation in accordance with the following formula:
##EQU119##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, the power spectrum derived from the following formula,
##EQU120##
has a plurality of peaks in a region in which n satisfies
##EQU121##
In this case, the peak value of the power spectrum is extremely
important. It is preferable that in the region where n satisfies
##EQU122##
the power spectrum have a plurality of peaks that satisfies the
conditions of ##EQU123##
more preferably ##EQU124##
furthermore preferably ##EQU125##
When ##EQU126##
the power of the wave is so weak that the effect of controlling the
regularity of the unevenness at the interface of the photosensitive
layer on the side of the support is small and therefore the
streaked images are apt to be formed.
Further, a photoreceptor having the following features is also
capable of reducing the formation of streaked images extremely
effectively: when a group of data which consists of N samples of
the height x(t) (.mu.m) of the profile of the surface of the
support, measured perpendicular to the horizontal direction of the
support, taken at .DELTA.t (.mu.m) intervals in the horizontal
direction, is subjected to discrete Fourier transformation in
accordance with the following formula: ##EQU127##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, a power spectrum derived from the following formula,
##EQU128##
has a plurality of peaks in a region in which n satisfies
##EQU129##
The unevenness with such a relatively large amplitude can be formed
on the surface of the support relatively easily by appropriately
selecting a cutting tool for use in machining, and by appropriately
setting the machining conditions. The wave with a large power has
surely an effect not only on the surface of the support, but also
on the surface of the undercoat layer so that care must be taken
with the above taken into consideration.
In this case, the peak value of the power spectrum is extremely
important. It is preferable that in the region where n satisfies
##EQU130##
the power spectrum have a plurality of peaks that satisfies the
conditions of ##EQU131##
more preferably ##EQU132##
furthermore preferably ##EQU133##
When ##EQU134##
the power of the wave is so weak that the effect of controlling the
regularity of the unevenness at the interface of the photosensitive
layer on the side of the support is small and therefore the
streaked images are apt to be formed.
It is known that the streaked image is formed when the amplitude of
the profile of the interface of the photosensitive layer on the
side of the support is large, and the period of the variations with
high regularity is about n times the period of the writing light
(where n is an integer), so that when the amplitude of the profile
of the interface of the photosensitive layer on the side of the
support is not made large, and the period of the variations with
high regularity is not made about n times the period of the writing
light, the streaked image is not formed.
However, the profile of the interface of the photosensitive layer
on the side of the support is composed of a number of waves, so
that it has been difficult to specify a wave with a large amplitude
and high regularity in the profile of the interface of the
photosensitive layer on the side of the support. For analyzing a
wave composed of such a large number of waves, Fourier
transformation is an extremely useful method and exhibits
outstanding power in abstracting waves which may form the streaked
image.
A photoreceptor having the following features is also capable of
completely controlling or removing the formation of streaked
images: when a group of data which consists of N samples of the
height x(t) (.mu.m) of the profile of the interface of the
photosensitive layer on the side of the support, measured
perpendicular to the horizontal direction of the support, taken at
.DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to discrete Fourier transformation in accordance with the
following formula: ##EQU135##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, in a power spectrum derived from the following formula,
##EQU136##
the relationship between the value of n, (n.sub.max), at which
##EQU137##
is maximized in the range of 1 to N/2, and the pitch W.sub.l
(.mu.m) of the writing light which is coherent light for image
formation is ##EQU138##
or ##EQU139##
where m is an integer obtained by rounding off the decimals of
##EQU140##
provided that when ##EQU141##
In an image formation apparatus of the present invention, there is
a case where image formation is carried out with the period of the
writing light being changed in accordance with the kind of image to
be output. In such a case, it is necessary that the writing light
satisfy the relationship of ##EQU142##
or ##EQU143##
for each period of the writing light.
In the photoreceptor in which the photosensitive layer is overlaid
on the support through the undercoat layer, the profile of the
undercoat layer corresponds to the profile of the interface of the
photosensitive layer on the side of the support as long as the
undercoat layer is not dissolved or swollen in the course of the
formation of the photosensitive layer, so that a photoreceptor
comprising the photosensitive layer on the support and having the
following features is capable of completely controlling or reducing
the formation of the streaked images: when a group of data which
consists of N samples of the height x(t) (.mu.m) of the profile of
the surface of the undercoat layer on the side of the
photosensitive layer, measured perpendicular to the horizontal
direction of the support, taken at .DELTA.t (.mu.m) intervals in
the horizontal direction, is subjected to discrete Fourier
transformation in accordance with the following formula:
##EQU144##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, in the power spectrum derived from the following formula,
##EQU145##
the relationship between the value of n, (n.sub.max), at which
##EQU146##
is maximized in the range of 1 to N/2, and the pitch W.sub.l
(.mu.m) of the writing light which is coherent light for image
formation is ##EQU147##
or ##EQU148##
where m is an integer obtained by rounding off the decimals of
##EQU149##
provided that when ##EQU150##
When a wave with a strong power is present in the profile of the
support, the wave intensely reflects upon the profile of the
interface of the photosensitive layer on the side of the support,
not only in the case where the undercoat layer is not provided, but
also in the case where the undercoat layer is provided, so that a
photoreceptor comprising the photosensitive layer on the support
and having the following features is capable of completely
controlling or reducing the formation of the streaked images: when
a group of data which consists of N samples of the height x(t)
(.mu.m) of the profile of the surface of the undercoat layer,
measured perpendicular to the horizontal direction of the support,
taken at .DELTA.t (.mu.m) intervals in the horizontal direction, is
subjected to discrete Fourier transformation in accordance with the
following formula: ##EQU151##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, in the power spectrum derived from the following formula,
##EQU152##
the relationship between the value of n, (n.sub.max) at which
##EQU153##
is maximized in the range of 1 to N/2, and the pitch W.sub.l
(.mu.m) of the writing light which is coherent light for image
formation is ##EQU154##
or ##EQU155##
where m is an integer obtained by rounding off the decimals of
##EQU156##
provided that when ##EQU157##
The photoreceptor of the present invention comprises the support
and the photosensitive layer comprising a charge generation
material and a charge transport material provided on the support as
mentioned above. When necessary, the undercoat layer can be
provided between the support and the photosensitive layer, and a
protective layer on the photosensitive layer.
The photoreceptor of the present invention may be (1) a layered
photoreceptor in which a charge generation layer comprising the
charge generation material and a charge transport layer comprising
the charge transport material are separately formed and overlaid to
form the photosensitive layer, or (2) a single layer photoreceptor
in which a mixture of the charge generation material and the charge
transport material is contained in the photosensitive layer, since
both of the photoreceptors exhibit excellent photoconductive
characteristics.
However, the layered photoreceptor is preferable in view of the
effects of ozone which is generated when charged in the course of
image formation, and also in view of the changes in the
chargeability and photosensitivity of the photoreceptor due to the
abrasion of the surface of the photoreceptor in the course of image
formation. In particular, preferred is a layered photoreceptor
which comprises the undercoat layer, the charge generation layer,
and the charge transport layer, which layers are successively
overlaid in this order on the support.
It is also preferable that the protective be provided on the
surface of the layered photoreceptor in order to control the
changes in the chargeability and photosensitivity of the
photoreceptor due to the abrasion of the surface of the
photoreceptor in the course of image formation. In particular, a
protective layer comprising a white pigment such as aluminum oxide
or titanium oxide is preferable.
The total thickness of the undercoat layer and the charge
generation layer of the layered photoreceptor of the present
invention is 15 .mu.m or less, preferably 12 .mu.m or less, more
preferably 8 .mu.m or less.
When the total thickness of the undercoat layer and the charge
generation layer of the layered photoreceptor of the present
invention is more than 15 .mu.m, since the unevenness of the
surface of the support is difficult to reflect on the bottom
surface of the charge transport layer, the light and shade image is
apt to be formed.
The thickness of the photosensitive layer of the photoreceptor of
the present invention is appropriately selected in accordance with
the electrostatic characteristics and resolution required by the
image formation apparatus in which the photoreceptor is employed.
For the attainment of high resolution effectively, the thickness of
the photosensitive layer is 15 .mu.m or less, preferably 14 .mu.m
or less.
A conventional photoreceptor with a photosensitive layer with a
thickness of 15 .mu.m or less can attain high resolution, but is
extremely apt to form images with the specific information of the
photoreceptor being superimposed on the written image, thereby
forming abnormal images including light and shade stripes. However,
the photoreceptor of the present invention practically do not
produce such abnormal images.
It is extremely important to precisely determine the interface of
the photosensitive layer on the side of the support, the surface of
the undercoat layer, and the interface of the undercoat layer on
the side of the support to control the formation of abnormal images
such as the light and shade striped image and the streaked
image.
Not only in the field of photoreceptors, but also in other fields,
such as in the studies of the adhesion of a solid material to
materials such as paint, the friction characteristics of a solid
with other materials, and the optical, electrical, and
electrochemical characteristics of a solid material, is it known
that these characteristics largely vary in accordance with the
profile of the surface of the solid material, so that precise
determination of the profile of the surface of solid materials is
required in many fields.
The profile of the surface of such solid materials is determined,
using parameters such as Center-line Mean Roughness (Ra), Maximum
Height (Rmax), Ten-point Mean Roughness (Rz), for instance, as
shown in Japanese Industrial Standards JIS B 0601.
However, there is a case where materials which are almost the same
in these parameters have significantly different characteristics.
In such a case, the profiles of the materials are conspicuously
different. It is extremely difficult to determine the profile of
the surface of a solid material by use of a reference profile. This
is because generally a profile is composed of a number of
superimposed waves, and there are not always waves in the same
shape in the horizontal direction. The regularity of the profile of
the surface of a solid material subjected to surface machining
tends to be broken, depending upon machining conditions, the
abraded conditions of each part of surface machining apparatus, and
the state of maintenance of the surface machining apparatus. This
makes it more difficult to determine the profile of the surface of
the solid material.
For instance, Japanese Laid-Open Patent Application 9-178470
discloses a method of determining a profile of the surface of a
solid material. In the method, the surface of a solid material is
evaluated based on a spectrum obtained by subjecting a profile of
the surface of the solid material to be measured to Fourier
transformation. In this method, the profile is decomposed into a
plurality of its constituent waves, and the wavelength of each of
the constituent waves can be determined, so that the determination
of the profile is easier than that of conventional methods.
Furthermore, this method is convenient to perform a new analysis of
the profile by eliminating or adding a particular wave.
The spectrum obtained by this method, however, also indicates a
number of weak waves so that the determination tends to be
imprecise. Furthermore, in many cases, the characteristics of the
solid surface correlate with the power of each wave, this method is
apt to provide misleading determination.
Power spectrum indicates the power of each wave and is most
suitable for evaluating the profile of a solid surface. In Japanese
Laid-Open Patent Application 7-128037, there is disclosed a method
of evaluating the surface roughness by the steps of subjecting the
surface wave of a machined surface to Fourier transformation, and
then performing a conversion to a frequency analysis relation
between a frequency and a power spectrum. In Japanese Laid-Open
Patent Application 7-128037, however, there is not disclosed a
specific method of determining the power spectrum. Furthermore, the
frequency is not described specifically, with the omission of the
unit of the frequency, so that the wavelength of the wave with each
frequency cannot be identified. In the case of a relative
evaluation conducted under constant measurement conditions with
respect to the profile of the solid surface, and under constant
analysis conditions, the above description may be acceptable.
Should there be a slight change in the measurement or analysis
conditions, no evaluation and determination of the profile can be
carried out by the method described in Japanese Laid-Open Patent
Application 7-128037.
The inventors of the present invention have discovered a method of
evaluating a solid surface, in particular, the interface of the
photosensitive layer of the photoreceptor on the side of the
support, the surface of the undercoat layer, and the surface of the
support, which method is carried out, not by the relative
evaluation as in Japanese Laid-Open Patent Application 7-128037,
but by such evaluation that can be done even if the measurement
conditions are changed.
More specifically, this method is carried out by the steps of
subjecting a group of data which consists of N samples of the
height x(t) (.mu.m) of a profile of a solid surface, measured
perpendicular to the horizontal direction of the solid surface,
taken at .DELTA.t (.mu.m) intervals in the horizontal direction of
the solid surface, to discrete Fourier transformation in accordance
with the following formula: ##EQU158##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, and comparing a power spectrum derived from the following
formula, ##EQU159##
with a specific reference.
More specifically, according to the present invention, there is
provided a method of evaluating a solid surface comprising the
steps of: measuring a group of data which consists of N samples of
the height x(t) (.mu.m) of a profile of the solid surface,
perpendicular to the horizontal direction of the solid surface,
taken at .DELTA.t (.mu.m) intervals in the horizontal direction of
the solid surface, subjecting the data group measured to discrete
Fourier transformation in accordance with formula (1):
##EQU160##
wherein n and m are an integer, and N=2.sup.p in which p is an
integer, calculating a power spectrum derived from formula (2):
##EQU161## comparing the power spectrum calculated with a specific
reference, thereby evaluating the solid surface.
Furthermore, according to the present invention, there is provided
a method of evaluating a solid surface comprising the steps of:
measuring a group of data which consists of N samples of the height
x(t) (.mu.m) of a profile of the solid surface, perpendicular to
the horizontal direction of the solid surface, taken at .DELTA.t
(.mu.m) intervals in the horizontal direction of the solid surface,
subjecting the data group measured to discrete Fourier
transformation in accordance with formula (1): ##EQU162##
calculating I(S) derived from formula (2) and formula (3):
##EQU163## and comparing the I(S) calculated with a specific
threshold value, thereby evaluating the solid surface.
Furthermore, according to the present invention, there is provided
a method of evaluating a solid surface comprising the steps of:
measuring a group of data which consists of N samples of the height
x(t) (.mu.m) of a profile of the solid surface, perpendicular to
the horizontal direction of the solid surface, taken at .DELTA.t
(.mu.m) intervals in the horizontal direction of the solid surface,
subjecting the data group measured to discrete Fourier
transformation in accordance with formula (1): ##EQU164##
calculating I(S) derived from formula (2) and formula (4):
##EQU165## wherein a and b are an integer of N or less, and
a.ltoreq.b, and comparing the I'(S) calculated with a specific
threshold value, thereby evaluating the solid surface.
Furthermore, according to the present invention, there is provided
a method of machining a solid surface by changing the machining
conditions for the solid surface based on any of the
above-mentioned methods of evaluating the solid surface.
An example of the present invention will now be explained, using
aluminum drums which are used as a support for a photoreceptor.
FIG. 2 shows a profile of an aluminum drum A which was cut with a
cutting machine equipped with a brand-new diamond cutting tool.
FIG. 3 shows a profile of an aluminum drum B which was cut with the
same cutting machine as mentioned above after 500 aluminum drums
were cut.
FIG. 4 shows the power spectrum of the aluminum drum A
(.DELTA.t=0.31 .mu.m, N=4096), and FIG. 5 shows the power spectrum
of the aluminum drum B (.DELTA.t=0.31 .mu.m, N=4096).
The profile of the aluminum drum A and the profile of the aluminum
drum B conspicuously differ. However, with respect to the
conventionally employed parameter of surface roughness, Ten-point
Mean Roughness (Rz), the two aluminum drums A and B are almost the
same.
With reference to their power spectrums, the two aluminum drums A
and B clearly differ.
In the aluminum drum A, most of the waves have a wavelength of 84.7
.mu.m (15/1270 .mu.m.sup.-1) and have a strong power. In the
aluminum drum B, however, in addition to the waves with a
wavelength of 84.7 .mu.m (15/1270 .mu.m.sup.-1), there are waves
with a wavelength of 635 .mu.m (2/1270 .mu.m.sup.-1), of which
power is significantly lower than the power of the waves with a
wavelength of 84.7 .mu.m.
Therefore, for instance, when a solid member for which a wave with
a particular wavelength is indispensable, or from which a wave with
a particular wavelength must be eliminated is prepared, the
existence or non existence of such a particular wave can be easily
seen or the degree of the power of the wave can be easily assessed
by checking the power spectrum of the member, so that it can be
extremely easily determined whether or not the solid member is
suitable for a particular purpose or within the scope of a
predetermined standard value.
When the solid member does not meet the requirement for the
standard value, surface machining conditions (in the case of
cutting, for instance, the feed rate and the speed of rotation of
the cutting tool, and the replacement of the cutting tool) are
immediately changed so as to produce a solid member that meets the
requirement for the standard value, whereby appropriate surface
machining can be carried out without producing inferior goods.
In many cases, such surface machining is often carried out at an
initial stage in the course of the production process including
many steps. Therefore if the evaluation of the solid surface is
improper, and some defects are caused by improper surface
machining, and found in the products at a final stage of the
production by final checking of the products, it is likely that
most of such products are inferior and cannot be used.
According to the present invention, the evaluation of the solid
surface in the surface machining process can be properly carried
out, and in case the evaluation indicates that the solid surface is
improper, the conditions for the surface machining are immediately
changed to proper conditions, without continuing the production, so
that the surface machining can always be carried out effectively
under appropriate conditions.
As the standard value for the power spectrum, a value is determined
by modifying the shape of the power spectrum or the power spectrum
itself, with the above-mentioned conditions being taken into
consideration that a wave with a particular wavelength is
indispensable, or a wave with a particular wavelength must be
eliminated, and the wave must have a particular power.
There are many cases where the adhesion characteristics of a solid
material to materials such as paint, the friction characteristics
of a solid material with other materials, and the optical,
electrical, and electrochemical characteristics of a solid material
correlate with I(S). In particular, in the photoreceptor
incorporated in the image formation apparatus which uses coherent
light as the writing light, I(S) of the surface of the support for
the photoreceptor conspicuously correlates the state of the
formation of the abnormal light and shade striped image.
The value of I(S), which is a threshold value, is appropriately
selected in accordance with an image formation process employed in
the image formation apparatus and the structure of the
photoreceptor incorporated in the image formation apparatus.
Usually, however, when the value of I(S) represented by the
following formula is 12.0.times.10.sup.-3 or more, the light and
shade striped image is not practically formed; ##EQU166##
It is necessary that the measurement range N.multidot..DELTA.t in
the horizontal direction of the profile be set so as to have an
appropriate length for transformation of a sufficient number of
waves in order to minimize the measurement error, since if the
measurement range N.multidot..DELTA.t is not long enough, the
number of waves to be transformed is so small that the measurement
error is increased. Furthermore, unless .DELTA.t is sufficiently
smaller than the wavelength of the wave to be judged, the error
with respect to the power of the wave to be judged tends to become
large.
In many cases, .DELTA.t is in the range of 0.01 .mu.m to 50.00
.mu.m, preferably in the range of 0.05 .mu.m to 40.00 .mu.m, more
preferably in the range of 0.10 .mu.m to 30.00 .mu.m.
When .DELTA.t is less than 0.01 .mu.m, an extremely large number of
samplings are required in order to sufficiently increase the
measurement range N.multidot..DELTA.t for the measurement, causing
a severe burden on the calculation, so that resultantly, the
measurement range T will have to be decreased, and accordingly the
error tends to be increased.
On the other hand, when at is more than 50.00 .mu.m, the waves with
short wavelengths which are concerned with the various
characteristics of the solid surface cannot be picked up, so that
it becomes to difficult to make an appropriate judgement of the
solid surface.
As to the number of samplings, unless the burden on the calculation
is taken into consideration, the greater, the better. Practically,
the number of samplings is 2048 or more, preferably 4096 or more,
more preferably 8192 or more, in order to reduce the error.
The inventors of the present invention have confirmed that with
respect to the profile of the support for the photoreceptor, the
power spectrum thereof sufficiently converges when the number of
samplings N is 4096 (N=4096), and the sampling interval .DELTA.t is
0.31 .mu.m (.DELTA.t=0.31 .mu.m).
Furthermore, I(S) calculated based on the following formula (5)
indicates the magnitude of variations of a solid surface and is a
new and extremely useful parameter for evaluating and judging the
solid surface: ##EQU167##
The inventors of the present invention have also confirmed that
with respect to the profile of the support for the photoreceptor,
the above-mentioned new parameter I(S) sufficiently converges
within several percent of error, when the number of samplings N is
4096 (N=4096), and the sampling interval .DELTA.t is 0.31 .mu.m
(.DELTA.t=0.31 .mu.m).
This can be considered from a different angle. When the sampling
interval (real space) of the measurement of the surface roughness
of a base pipe is .DELTA.t[.mu.m], the sampling interval
(reciprocal space) of the power spectrum is
.DELTA.n=1/(N.multidot..DELTA.t) [.mu.m.sup.-1 ]. This is because
the domain of definition of the height x(t) of the profile is the
interval of T-N.multidot..DELTA.t. This indicates that the original
signal x(t) can be reproduced by the Fourier spectrum of the value
of the sample with the intervals of .DELTA.n
(=1/(N.multidot..DELTA.t)) in the reciprocal space. The variation
period of the profile that can be reproduced here is approximately
2.DELTA.t in accordance with Shannon's sampling theorem.
With respect to the phenomenon now in consideration, a surface
roughness with a variation period above the above-mentioned
variation period is involved, so that the sampling interval of
.DELTA.t (=0.31 [.mu.m]) is sufficient when the phenomenon differs,
it may be necessary to consider a more minute variation period. In
such a case, the sampling interval is shortened in accordance with
the variation period.
The evaluation and judgement using I(S) has been conducted here
with respect to the waves with all the wavelengths which constitute
the profile. However, when it is known that waves with wavelengths
in a particular region correlates the characteristics, the
evaluation and judgement may be carried out by limiting the
integration range of the power spectrum to the region of the
necessary wavelengths.
More specifically, when attention is paid to the waves with a
wavelength of N.multidot..DELTA.t/b-N.multidot..DELTA.t/a .mu.m, in
which a and b are an integer of N or less, and a.ltoreq.b, I'(S)
calculated based on the following formula (6) can be used as a
parameter for evaluating and judging the solid surface:
##EQU168##
As the support for the photoreceptor of the present invention,
there can be employed, for example, (1) a drum or a belt made of a
metal such as copper, aluminum, gold, platinum, iron, palladium, or
an alloy comprising any of such metals, and (2) a belt composed of,
for example, a plastic film on which any of the above-mentioned
metals, or a metal oxide such as tin oxide or indium oxide, is
deposited, for example, by vacuum deposition or electroless
plating.
It is preferable that the surface of the support be subjected to
surface processing by overlaying the undercoat layer, forming an
anodic oxidation film, machining, blasting, or honing, in order to
improve the bonding between the photosensitive layer and the
support.
Furthermore, in order to control the formation of the abnormal
images such as the light and shade striped image and the streaked
image, it is preferable that the surface of the support be
roughened so as to have the profile as mentioned above by
controlling the composition of the support or the conditions for
preparing the support, or by use of other methods such as physical
and electrochemical methods.
Of these methods, the physical methods such as machining, blasting,
and honing have a high roughening effect and are preferable.
Machining is particularly effect and most preferable for use in the
present invention.
The profile of the surface of the support in the above-mentioned
state can be obtained by controlling the shape of the top edge of
the cutting tool or controlling the feeding speed of the cutting
tool, or by use of a plurality of cutting tools.
It is also effective to roughen the surface of the support by other
method before or after machining the surface of the support.
Examples of the undercoat layer for the photoreceptor of the
present invention are an undercoat layer made of a resin, an
undercoat layer composed of a white pigment and a resin as the main
components, and a film made of a metal oxide formed by chemically
or electrochemically oxidizing an electroconductive surface of the
support.
Of the above-mentioned examples, the undercoat layer composed of a
white pigment and a resin as the main components is preferable
since the profile of the surface of the undercoat layer can be
controlled so as to be in the above-mentioned state.
As the white pigment, metal oxides such as titanium oxide, aluminum
oxide, zirconium oxide, and zinc oxide can be employed. Of these
metal oxides, titanium oxide is most preferable for use in the
present invention since it has an excellent charge injection
prevention effect by which the injection of electric charges from
the electroconductive support can be most effectively
prevented.
Examples of the resin for use in the undercoat layer are
thermoplastic resins such as polyamide, polyvinyl alcohol, casein
and methyl cellulose, hardening resins such as acrylic-resin,
phenolic resin, melamine resin, alkyd resin, unsaturated polyester
resin and epoxy resin, a mixture of these resins.
Examples of the charge generation material for use in the
photoreceptor of the present invention are organic pigments and
dyes, such as monoazo pigment, bisazo pigment, trisazo pigment,
tetrakisazo pigment, triarylmethane dye, thiazine dye, oxazine dye,
xanthene dye, cyanine dye, styryl dye, pyrylium dye, quinacridone
pigment, indigo pigment, perylene pigment, polycyclic quinone
pigment, bisbenzimidazole pigment, indanthrone pigment, squarylium
pigment, and phthalocyanine pigment; and inorganic materials such
as selenium, selenium--arsenic, selenium--tellurium, cadmium
sulfide, zinc oxide, titanium oxide and amorphous silicon.
The charge generation layer can be formed of one or more charge
generation materials mentioned above in combination with a binder
resin.
Examples of the charge transport material for use in the
photoreceptor of the present invention are an anthracene
derivative, a pyrene derivative, a carbazole derivative, a
tetrazole derivative, a metallocene derivative, a phenothiazine
derivative, a pyrazoline compound, a hydrazone compound, a styryl
compound, a styryl hydrazone compound, an enamine compound, a
butadiene compound, a distyryl compound, an oxazole compound, an
oxadiazole compound, a thiazole compound, an imidazole compound,
triphenylamine derivative, a phenylenediamine derivative, an
aminostilbene derivative and a triphenylmethane derivative. One or
more The charge transport layer can be formed of one or more charge
transport materials mentioned above in combination with a binder
resin.
It is required that the binder resin for use in the charge
generation layer and the charge transport layer be electrically
insulating.
As the binder resin, conventionally known thermoplastic resin,
thermosetting resin, photo-setting resin, and photoconductive resin
can be employed.
More specifically, there can be employed thermoplastic resins such
as polyvinyl chloride, polyvinylidene chloride, vinyl
chloride--vinyl acetate copolymer, vinyl chloride--vinyl
acetate--maleic anhydride copolymer, ethylene--vinyl acetate
copolymer, polyvinyl butyral, polyvinyl acetal, polyester, phenoxy
resin, (meth)acrylic resin, polystyrene, polycarbonate,
polyarylate, polysulfone, polyether sulfone and ABS resin;
thermosetting resins such as phenolic resin, epoxy resin, urethane
resin, melamine resin, isocyanate resin, alkyd resin, silicone
resin and thermosetting acrylic resin; and photoconductive resins
such as polyvinyl carbazole, polyvinyl anthrasene and polyvinyl
pyrene.
These resins can be employed alone or in combination, although the
binder resin for use in the present invention is not limited to the
above-mentioned examples.
The photoreceptor of the present invention, when incorporated in
image formation apparatus such as copying machines, printers, and
facsimile apparatus and used for image formation, is capable of
forming images with extreme high quality.
The image formation apparatus of the present invention, in which
the above-mentioned photoreceptor is incorporated, is capable of
forming high quality images using as the writing light either
incoherent light or coherent light. However, when coherent light is
used as the writing light, abnormal images such as the light and
shade striped image are not formed, so that by use of coherent
light, image formation with high image quality, with high
resolution and high precision can be carried out.
The image formation apparatus in which the photoreceptor of the
present invention is incorporated is capable of forming high
quality images with any spot diameter of the writing light, and the
spot diameter can be appropriately selected in accordance with the
desired image resolution. The spot diameter is preferably 80 .mu.m
or less, more preferably 70 .mu.m or less, furthermore preferably
60 .mu.m or less.
An image formation apparatus in which a conventional photoreceptor
is incorporated, with the spot diameter of the writing light set at
80 .mu.m or less, is capable of forming images with high
resolution. However, in the image formation, information peculiar
to the photoreceptor is apt to be superimposed on the writing
image, so that in such a conventional image formation apparatus,
abnormal images such as the light and shade striped image are
extremely apt to be formed. In sharp contrast to this, in the image
formation apparatus of the present invention, such abnormal images
are not practically formed.
There is no restriction on the wavelength of the writing light, but
it is preferable that the wavelength be 700 nm or less, more
preferably 675 nm or less, furthermore preferably 400 nm to 600 nm.
Even when there is used the write light with such a short
wavelength that makes it possible to form the writing image with
high resolution, the image formation apparatus of the present
invention can form high quality images with high resolution and
high precision, without forming the abnormal images such as the
light and shade striped image and the streaked image.
There is no particular restriction on the gradation reproduction
method for forming the writing image for use in the image formation
apparatus of the present invention.
When a multivalued gradation reproduction method is employed, the
density of picture element is set at multiple steps, so that in the
case of the image formation apparatus using a conventional
photoreceptor, the light and shade striped image is apt to become
conspicuous. In particular, this tendency is increased extremely
high, particularly when pulse width modulation or power modulation
is employed, and when pulse width modulation and power modulation
are employed in combination. However, in the case of the image
formation apparatus using the photoreceptor of the present
invention, no light and shade image is formed even when the
multivalued gradation reproduction method is employed.
There is no restriction on the resolution of the writing image for
the image formation apparatus. The image formation apparatus is
capable of forming high quality images at a resolution as high as
600 dpi or more, even at 1000 dip or more. In the writing image at
such a high resolution, image formation is apt to be carried out
with the information peculiar to the photoreceptor being
superimposed on the writing image, so that in the case of the image
formation apparatus in which a conventional photoreceptor is used,
abnormal images including the light and shade striped image are
extremely apt to formed. However, in the case of the image
formation apparatus using the photoreceptor of the present
invention, such abnormal images are not practically formed.
Other features of this invention will become apparent in the course
of the following description of exemplary embodiments, which are
given for illustration of the invention and are not intended to be
limiting thereof.
EXAMPLE 1
Four aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a diamond cutting tool.
The profile of the surface of the third machined aluminum drums was
measured by use of a surface roughness meter (Surfcom 1400A). As a
result, a profile as shown in FIG. 6 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 7 was prepared. I(S) was then calculated. The result was
that I(S) was 21.8.times.10.sup.-3.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
The surface of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A). As a result, a profile as
shown in FIG. 8 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 9 was prepared. I(S) was then calculated. The result was
that I(S) was 17.4.times.10.sup.-3.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of a trisazo
pigment with the following formula were added, and the mixture was
dispersed for 48 hours: ##STR1##
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 3 hours. The
dispersion was then diluted with cyclohexanone, with stirring, in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid for the formation of a charge
generation layer and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the undercoat layer of the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge generation layer with a thickness of about 0.2
.mu.m was formed on the undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 90 parts by
weight of methylene chloride:
Parts by weight Charge transport material with the following
formula: 6 ##STR2## Polycarbonate resin (Trademark "Panlite K-1300"
made by 10 Teijin Limited) Silicone oil (Trademark "KF-50" made by
Shin-Etsu 0.002 Chemical Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
for the formation of a charge transport layer and then pulled up
vertically at a predetermined constant speed, whereby the coating
liquid was coated on the surface of the charge generation layer of
the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge transport layer with a thickness of about 23 .mu.m
was formed on the charge generation layer of the aluminum drum.
Thus, a photoreceptor of the present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm, with writing image with a resolution of 400
dpi, and with 256 gradations in combination of pulse width
modulation and power modulation.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
EXAMPLE 2
The procedure of preparing the photoreceptor of the present
invention in Example 1 was repeated in the same manner as in
Example 1 except that the thickness of the undercoat layer was
changed to 7.0 .mu.m, whereby a photoreceptor of the present
invention was prepared.
A profile of the surface of the undercoat layer as shown in FIG. 10
was obtained in the same manner as in Example 1. From the profile,
a graph of a power spectrum of the surface of the undercoat layer
was prepared as shown in FIG. 11, and I(S) was calculated. The
result was that I(S) was 15.4.times.10.sup.-3.
By use of the copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 1
500 aluminum drums were machined by use of the same cutting tool as
used in Example 1, and a photoreceptor was prepared by use of the
500th machined aluminum drum in the same manner as in Example
1.
A profile of the outer surface of the aluminum drum as shown in
FIG. 12 was obtained in the same manner as in Example 1. From the
profile, a graph of a power spectrum of the surface of the aluminum
drum was prepared as shown in FIG. 13, and I(S) was calculated. The
result was that I(S) was 11.1.times.10.sup.-3.
A profile of the surface of the undercoat layer as was also
obtained in the same manner as in Example 1. From the profile, a
graph of a power spectrum of the surface of the undercoat layer was
prepared, and I(S) was calculated. The result was that I(S) was
5.6.times.10.sup.-3.
By use of the copying machine with the photoreceptor incorporated
therein, a monochrome halftone image which was uniform in its
entirety was copied and output. As a result, an image with
non-uniform light and shade portions near the edge portion of the
image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. A close inspection of the obtained
image indicated that the image included slightly non-uniform light
and shade portions near the edge portion of the image.
EXAMPLE 3
The procedure of the image formation in Example 1 was repeated in
the same manner as in Example 1 except that the copying machine
employed in Example 1 was modified so as to be capable of writing
with writing image with a resolution of 1200 dpi.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the modified copying
machine, a uniform image free of abnormal images such as the light
and shade striped image was obtained, and when a full-color
landscape photograph was also copied by use of the copying machine,
a high quality image was obtained.
COMPARATIVE EXAMPLE 2
The procedure of the image formation in Example 3 was repeated in
the same manner as in Example 3 except that the photoreceptor
employed in Example 3 was replaced by the photoreceptor prepared in
Comparative Example 1.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the modified copying
machine using the photoreceptor, an image with 4 sets of light and
shade stripes in a band shape near the edge portion of the image
was obtained.
Furthermore, light and shade stripes with a period corresponding to
the photoreceptor, with a light-grained pattern, were also
recognized in the image When. a full-color landscape photograph was
also copied by use of the copying machine, an image including
band-shaped abnormal images near the edge portion of the image was
obtained. In the obtained color image, the portion in a position
which almost corresponded in terms of the height to the portion of
the light and shade stripes recognized when the monochrome half
tone image was copied partially included a slightly unnatural color
tone portion.
The profile of the aluminum drum of the photoreceptor employed in
both Comparative Examples 1 and 2 was in such a shape that the
sub-peaks were superimposed on the main peaks. However, it was
impossible to prevent the formation of the abnormal light and shade
striped image by such profile of the aluminum drum.
The above results clearly indicates that in order to prevent the
formation of the abnormal light and shade striped image, it is
extremely important to set the value of I(S) of the profile at an
appropriate value.
EXAMPLE 4
The procedure of preparing the photoreceptor of the present
invention in Example 1 was repeated in the same manner as in
Example 1 except that the thickness of the charge transport layer
was changed to 14.5 .mu.m, whereby a photoreceptor of the present
invention was prepared.
The procedure of the image formation in Example 3 was repeated in
the same manner as in Example 3 except that the photoreceptor
employed in the modified copying machine was replaced by the above
photoreceptor of the present invention.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the modified copying
machine using the photoreceptor No. 3 of the present invention, a
uniform image free of abnormal images such as the light and shade
striped image was obtained, and when a full-color landscape
photograph was also copied by use of the copying machine, a high
quality image was obtained.
COMPARATIVE EXAMPLE 3
The procedure of preparing the photoreceptor in Comparative Example
1 was repeated in the same manner as in Comparative Example 1
except that the thickness of the charge transport layer was changed
to 14.5 .mu.m, whereby a photoreceptor was prepared.
The procedure of the image formation in Comparative Example 2 was
repeated in the same manner as in Comparative Example 2 except that
the photoreceptor employed in Comparative Example 2 was replaced by
the above prepared photoreceptor.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the modified copying
machine using the photoreceptor, an image with 5 sets of light and
shade stripes in a band shape near the edge portion of the image
was obtained. Furthermore, light and shade stripes with a period
corresponding to the photoreceptor, with a light-grained pattern
were also recognized in the image. When a full-color landscape
photograph was also copied by use of the copying machine, an image
including band-shaped abnormal images near the edge portion of the
image was obtained. In the obtained color image, the portion in a
position which almost corresponded in terms of the height to the
portion of the light and shade stripes recognized when the
monochrome half tone image was copied partially included a slightly
unnatural color tone portion.
EXAMPLE 5 TO 10 AND COMPARATIVE EXAMPLES 4 AND 5
500 aluminum drums with the same size as that of the aluminum drums
employed in Example 1 were prepared by use of a brand-new diamond
cutting tool which of the same type as that of the cutting tool
employed in Example 1.
Of these drums, 8 drums were subjected to random sampling, and the
profile of the outer surface of each of the sampled drums was
measured in the same manner as in Example 1 and the values of the
respective I(S) were determined.
By use of the sampled drums, 8 photoreceptors were prepared in the
same manner as in Example 1.
By incorporating each of the thus prepared photoreceptors in the
modified copying machine employed in Example 3, a monochrome
halftone image which was uniform in its entirety was copied and
output, so that the output images were evaluated with respect to
the presence of the abnormal light and shade striped image, with
the following evaluation ranking scale: 4: free of the abnormal
image 3: the abnormal image can be recognized only by close
inspection 2: the abnormal image can be slightly recognized 1: the
abnormal image can be conspicuously recognized
The results were as shown in TABLE 1:
TABLE 1 I(S) Evaluated Rank Example 5 41.0 .times. 10.sup.-3 4
Example 6 25.3 .times. 10.sup.-3 4 Example 7 23.4 .times. 10.sup.-3
4 Example 8 16.8 .times. 10.sup.-3 4 Example 9 14.6 .times.
10.sup.-3 3 Example 10 13.0 .times. 10.sup.-3 3 Comp. Example 4
10.9 .times. 10.sup.-3 2 Comp. Example 5 6.8 .times. 10.sup.-3
1
EXAMPLE 11
An aluminum drum with a diameter of 90 mm, a length of 352 mm, and
a wall thickness of 2 mm, which was not subjected to surface
machining, was coated with the same coating liquid for the
formation of an undercoat layer as that employed in Example 1 by
spray coating, using a pray gun.
The aluminum drum was transported into a drying chamber, where the
aluminum drum was dried at 140.degree. C. for 20 minutes. Thus, an
undercoat layer with a thickness of 4.0 .mu.m was formed on the
aluminum drum.
The profile of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A).
From the profile, sampling was conducted with .DELTA.t=2500/4096
.mu.m, and N=4096, so that I(S) and Ten-point Mean Roughness (Rz)
thereof were determined. The results are shown in TABLE 2.
By use of the above aluminum drum with the undercoat layer, a
photoreceptor of the present invention was prepared in the same
manner as in Example 1.
By incorporating the above photoreceptor in the copying machine
employed in Example 1, a monochrome halftone image which was
uniform in its entirety was copied and output. The output image was
uniform and free of the abnormal light and shade striped image.
EXAMPLES 12 AND 13, AND COMPARATIVE EXAMPLE 6 AND 7
The procedure of preparing the photoreceptor in Example 11 was
repeated in the same manner as in Example 11 except that the outer
surface of each of 4 drums was coated with the same coating liquid
for the formation of an undercoat layer as that employed in Example
11 by spray coating, using a pray gun, and that the moving speed of
the spray gun and the amount of the coating liquid ejected from the
spray gun were changed.
Each aluminum drum was transported into a drying chamber, where the
aluminum drum was dried at 140.degree. C. for 20 minutes. Thus, an
undercoat layer with a thickness of 4.0 .mu.m was formed on the
aluminum drum.
The profile of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A).
From the profile, sampling was conducted with .DELTA.t=2500/4096
.mu.m, and N=4096, so that I(S) and Ten-point Mean Roughness (Rz)
thereof were determined. The results are shown in TABLE 2.
By use of the above aluminum drums with the undercoat layer, four
photoreceptors were prepared in the same manner as in Example
11.
By incorporating each of the above photoreceptors in the copying
machine employed in Example 1, a monochrome halftone image which
was uniform in its entirety was copied and output. The output
images evaluated. The results are shown in TABLE 2.
TABLE 2 Rz I(S) Evaluation of Image Example 11 0.42 .mu.m 13.6
.times. 10.sup.-3 Uniform, no abnormal images Example 12 0.38 .mu.m
10.4 .times. 10.sup.-3 Uniform, no abnormal images Example 13 0.38
.mu.m 7.9 .times. 10.sup.-3 Uniform, no abnormal images Comparative
0.41 .mu.m 5.2 .times. 10.sup.-3 3 sets of light and shade streaks
Example 6 in the end portions of images Comparative 0.39 .mu.m 4.8
.times. 10.sup.-3 3 sets of light and shade streaks Example 7 in
the end portions of images, and grained light and shade stripes
The above results indicate that the Ten-point Mean Roughness (Rz)
of the undercoat layer has nothing to do with the evaluation of the
images, but when I(S) is 6.0.times.10.sup.-3 or more, high quality
image formation can be carried out.
EXAMPLE 14
Four aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a diamond cutting tool.
The outer surface of each of the aluminum drums was measured by use
of a surface roughness meter (Surfcom 1400A). As a result, a
profile as shown in FIG. 14 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 15 was prepared.
When the spot diameter of writing light was 70 .mu.m, a maximum
integer "j" that satisfies 4096.times.0.31/j.gtoreq.70/2 is 36, so
that I'(S) was calculated. The result was that I'(S) was
7.3.times.10.sup.-3.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface of the aluminum drum was roughened by machining. The
surface-roughened aluminum drum was immersed in the above prepared
coating liquid and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of the same
trisazo pigment as that employed in Example 1 were added, and the
mixture was dispersed for 48 hours.
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 10 hours. The
dispersion was then diluted with cyclohexanone in such a manner
that the amount ratio of the solid components in the dispersion was
1.5 wt. %, whereby a coating liquid for the formation of a charge
generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the undercoat layer of the aluminum drum.
The aluminum drum was dried in the same manner as for the undercoat
layer at 120.degree. C. for 20 minutes, whereby a charge generation
layer with a thickness of about 0.2 .mu.m was formed on the
undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 10 parts by
weight of tetrahydrofuran:
Parts by weight Charge transport material with the following
formula: 1 ##STR3## Bisphenoyl Z-type polycarbonate resin 1
Silicone oil (Trademark "KF-50" made by Shin-Etsu 0.02 Chemical
Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
and then pulled up vertically at a predetermined constant speed,
whereby the coating liquid was coated on the surface of the charge
generation layer of the aluminum drum.
The aluminum drum was dried in the same manner as for the undercoat
layer at 120.degree. C. for 20 minutes, whereby a charge transport
layer with a thickness of about 23 .mu.m was formed on the charge
generation layer of the aluminum drum. Thus, a photoreceptor of the
present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm and a spot diameter of writing light of 70
.mu.m.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
EXAMPLE 15
An aluminum drum was prepared in the same manner as in Example 14
except that the diamond cutting tool employed in Example 14 was
replaced with a brand-new diamond cutting tool.
The profile of the aluminum drum was measured and I'(S) was
calculated with J=36 in the same manner as in Example 14. The
result was that I'(S) was 13.9.times.10.sup.-3,
By use of this aluminum drum, a photoreceptor of the present
invention was prepared in the same manner as in Example 1 except
that the thickness of the undercoat layer was changed to 7.0
.mu.m.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output in the same
manner as in Example 14. As a result, a uniform image free of
abnormal images such as the light and shade striped image was
obtained.
Furthermore, the full-color landscape photograph employed in
Example 1 was also copied by use of this copying machine. As a
result, a high quality image was obtained.
EXAMPLE 16
A photoreceptor of the present invention was prepared in the same
manner as in Example 15 except that the thickness of the undercoat
layer was changed to 15.8 .mu.m.
The profile of the aluminum drum for this photoreceptor was
measured and I'(S) was calculated with J=36 in the same manner as
in Example 15. The result was that I'(S) was
14.0.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that used in Example 14.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output in the same
manner as in Example 14. As a result, an image with band-shaped,
non-uniform light and shade portions in the edge portion thereof
was obtained.
Furthermore, the full-color landscape photograph employed in
Example 1 was also copied by use of this copying machine. As a
result, a high quality image was obtained.
COMPARATIVE EXAMPLE 8
400 aluminum drums were machined by use of the same cutting tool as
that used in Example 14. By use of the aluminum drum, a
photoreceptor of the present invention was prepared in the same
manner as in Example 14.
FIG. 16 shows the profile of the aluminum drum of the
photoreceptor. As shown in FIG. 16, the profile was in such a shape
that the sub-peaks were superimposed on the main peaks.
A power spectrum of the profile was prepared as shown in FIG. 17,
and I(S) was calculated with J=36. The result was that I(S) was
3.9.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that used in Example 14.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output in the same
manner as in Example 14. As a result, an image with conspicuous
band-shaped, non-uniform light and shade portions, together with
grained light and shade stripes, in the edge portion thereof was
obtained.
Furthermore, the full-color landscape photograph employed in
Example 1 was also copied by use of this copying machine. As a
result, the edge portion of the obtained image appeared
unnatural.
EXAMPLE 17
120 aluminum drums were machined by use of the same cutting tool as
that used in Example 15. By use of the aluminum drum, a
photoreceptor of the present invention was prepared in the same
manner as in Example 14.
When the spot diameter of writing light was set at 50 .mu.m, J=50.
I'(S) of the profile of the surface of the aluminum drum, with
J=50, was calculated. The result was that I'(S) was
6.9.times.10.sup.-3.
A commercially available copying machine (Trademark "Imagio Color
2800" made by Ricoh Company, Ltd.) was modified to as to be capable
of writing with a spot diameter of writing light of 50 .mu.m.
The above photoreceptor was incorporated in this copying
machine.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output in the same
manner as in Example 14. As a result, a uniform image free of
abnormal images such as the light and shade striped image was
obtained.
Furthermore, the full-color landscape photograph employed in
Example 14 was also copied by use of this copying machine. As a
result, a high quality image was obtained.
EXAMPLE 18
An aluminum drum was machined by use of the same cutting tool as
that used in Example 17.
With the spot diameter of writing light set at 50 .mu.m, and with
J=50, I'(S) of the profile of the surface of the aluminum drum was
calculated. The result was that I'(S) was 0.0229.
By use of this aluminum drum, a photoreceptor of the present
invention was prepared in the same manner as in Example 14 except
that the thickness of the charge transport layer was changed to
14.5 .mu.m.
A commercially available copying machine (Trademark "Imagio Color
2800" made by Ricoh Company, Ltd.) was modified to as to be capable
of writing with a spot diameter of writing.light of 50 .mu.m.
The above photoreceptor was incorporated in this copying
machine.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output in the same
manner as in Example 14. As a result, an image free with 5 sets of
band-shaped, light and shade stripes in the end portion thereof was
obtained. In addition, grained light and shade stripes were
recognized at 283 mm intervals, corresponding to the
circumferential length of the drum-shaped photoreceptor employed in
this example.
EXAMPLE 19
An aluminum drum with a diameter of 90 mm, a length of 352 mm, and
a wall thickness of 2 mm was prepared by subjecting the outer
surface of the aluminum drum to honing to roughen the surface
thereof.
The profile of the roughened surface of the aluminum drum was
measured by use of a surface roughness meter (Surfcom 1400A). From
this profile, sampling was conducted with .DELTA.t 0.31 .mu.m, and
N=4096, and the thus obtained samples were subjected to discrete
Fourier transformation, whereby a power spectrum.was prepared. I(S)
was then calculated. The result was that I(S) was
18.1.times.10.sup.-1.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 120 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
The aluminum drum was then dried at 130.degree. C. for 20 minutes,
whereby an undercoat layer with a thickness of 4.8 .mu.m was formed
on the aluminum drum.
The profile of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A) in the same manner as in
the profile of the surface of the aluminum drum, and from this
profile, I(S) was then calculated. The result was that I(S) was
10.9.times.10.sup.-3.
Formation of Charge Generation Layer
2 parts by weight of butyral resin (Trademark "XYHL" made by Union
Carbide Japan K.K.) were dissolved in 200 parts by weight of methyl
ethyl ketone. To this solution, 10 parts by weight of a bisazo
pigment with the following formula were added, and the mixture was
dispersed for 40 hours: ##STR4##
To the above dispersion, 200 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 10 hours. The
dispersion was then diluted with cyclohexanone with stirring in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid and then pulled up, whereby the
coating liquid was coated on the surface of the undercoat layer of
the aluminum drum.
The aluminum drum was dried in the same manner as for the undercoat
layer at 120.degree. C. for 20 minutes, whereby a charge generation
layer with a thickness of about 0.2 .mu.m was formed on the
undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 10 parts by
weight of tetrahydrofuran:
Parts by weight Charge transport material with the following
formula: 1 ##STR5## Bisphenoyl Z-type polycarbonate resin 1
Silicone oil (Trademark "KF-50" made by Shin-Etsu Chemical 0.02
Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
and then pulled up, whereby the coating liquid was coated on the
surface of the charge generation layer of the aluminum drum.
The aluminum drum was dried in the same manner as for the undercoat
layer at 120.degree. C. for 20 minutes, whereby a charge transport
layer with a thickness of about 14 .mu.m was formed on the charge
generation layer of the aluminum drum. Thus, a photoreceptor of the
present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) which was modified so as to be capable of
writing with writing light with a wavelength of 655 nm and writing
image with a resolution of 1200 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, the same full-color landscape photograph as employed
in Example 1 was also copied by use of this copying machine. As a
result, a high quality image was obtained.
EXAMPLES 20 TO 23 AND COMPARATIVE EXAMPLE 9 AND 10
Six aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by subjecting the outer
surface of each of the aluminum drums to honing to roughen the
surface thereof in the same manner as in Example 19.
The outer surface of each of the six aluminum drums was coated with
the same coating liquid for the formation of an undercoat layer as
that employed in Example 19 by spray coating, using a pray gun,
with the moving speed of the spray gun and the amount of the
coating liquid ejected from the spray gun being changed, and was
then dried at 130.degree. C. for 20 minutes. Thus, an undercoat
layer with a thickness of about 4.5 .mu.m was formed on each of the
aluminum drums.
On the undercoat layer of each of the aluminum drums, the same
charge generation layer and the same charge transport layer as in
Example 19 were successively overlaid in the manner as in Example
19, whereby six photoreceptors of the present invention were
prepared.
Each of the thus prepared photoreceptors was incorporated in a
commercially available copying machine (Trademark "Imagio Color
2800" made by Ricoh Company, Ltd.) which was modified so as to be
capable of writing with writing light with a wavelength of 504 nm,
with writing image with a resolution of 1200 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output.
The profile of the surface of the undercoat layer of each of the
photoreceptors was measured, I(S) thereof was calculated, and the
image out was evaluated with respect to each of the photoreceptors.
The results are shown in TABLE 3.
TABLE 3 I(S) Evaluation of Image Example 20 12.5 .times. 10.sup.-3
Uniform, no abnormal images Example 21 11.7 .times. 10.sup.-3
Uniform, no abnormal images Example 22 9.9 .times. 10.sup.-3
Uniform, no abnormal images Example 23 8.5 .times. 10.sup.-3
Uniform, no abnormal images Comp. Example 9 5.7 .times. 10.sup.-3 3
sets of light and shade streaks in the end portions of images Comp.
Example 10 5.1 .times. 10.sup.-3 4 sets of light and shade streaks
in the end portions of images
EXAMPLE 24
100 aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a cutting tool with a 2.2 R diamond
point.
Of the thus machined aluminum drums, the profile of the outer
surface of a 75th machined aluminum drum was measured by use of a
surface roughness meter (Surfcom 1400A). As a result, a profile as
shown in FIG. 18 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 19 was prepared.
In the power spectrum, there were 6 peaks which satisfied
150.times.10.sup.-6.times.4096=0.614 or more in a region where n
satisfied ##EQU169##
namely in a region of 50.gtoreq.n.gtoreq.7.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 24.4.times.10.sup.-3.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
The surface of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A). As a result, a profile as
shown in FIG. 20 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 21 was prepared.
In the power spectrum, there were 4 peaks which satisfied
100.times.10.sup.-6.times.4096=0.410 or more in a region where n
satisfied ##EQU170##
namely in a region of 50.DELTA.n.gtoreq.7.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 8.02.times.10.sup.-3.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of a trisazo
pigment with the following formula were added, and the mixture was
dispersed for 48 hours: ##STR6##
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 3 hours. The
dispersion was then diluted with cyclohexanone, with stirring, in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid for the formation of a charge
generation layer and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the undercoat layer of the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge generation layer with a thickness of about 0.2
.mu.m was formed on the undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 90 parts by
weight of methylene chloride:
Parts by weight Charge transport material with the following
formula: 6 ##STR7## Polycarbonate resin (Trademark "Panlite K-1300"
made by 10 Teijin Limited) Silicone oil (Trademark "KF-50" made by
Shin-Etsu 0.002 Chemical Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
for the formation of a charge transport layer and then pulled up
vertically at a predetermined constant speed, whereby the coating
liquid for the formation of a charge transport layer was coated on
the surface of the charge generation layer of the aluminum
drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge transport layer with a thickness of about 24 .mu.m
was formed on the charge generation layer of the aluminum drum.
Thus, a photoreceptor of the present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm, and with writing image with a resolution of
400 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
EXAMPLE 25
A photoreceptor was prepared in the same manner as in Example 24
except that a 76th machined aluminum drum was employed and that the
thickness of the undercoat layer was changed to 4.0 .mu.m.
A profile of the surface of the undercoat layer was prepared in the
same manner as in Example 24. From the profile, the power spectrum
thereof was prepared. The result was that in the power spectrum,
there were 3 peaks which satisfied
100.times.10.sup.-6.times.4096=0.410 or more in a region where n
satisfies ##EQU171##
namely in a region of 50.gtoreq.n.gtoreq.7.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 6.74.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 24.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 11
A photoreceptor was prepared in the same manner as in Example 24
except that the cutting tool employed in Example 24 was replaced by
a cutting tool with a 1.6 R diamond point and that a 3rd machined
aluminum drum was employed.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 24. From the profile, a power spectrum
thereof was prepared as shown in FIG. 22. The result was that in
the power spectrum, there was only one peak which satisfied
150.times.10.sup.-6.times.4096=0.614 or more a region where n
satisfied ##EQU172##
namely in a region of 5.gtoreq.n.gtoreq.7.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 24.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image with streaks running in the
circumferential direction of the photoreceptor over an about 35%
area of the entire image area thereof.
COMPARATIVE EXAMPLE 12
A photoreceptor was prepared in the same manner as in Example 24
except that further 131 aluminum drums were machined and a 231st
machined aluminum was employed.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 24. From the profile, a power spectrum
thereof (not shown) was prepared. The result was that in the power
spectrum, there were 6 peaks which satisfied
150.times.10.sup.-6.times.4096=0.614 or more in a region where n
satisfies ##EQU173##
namely in a region of 50.gtoreq.n.gtoreq.7.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 11.6.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 24.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image free of lengthwise streaks running in
the circumferential direction of the photoreceptor, but light and
shade streaks were slightly recognized near one end portion of the
image.
EXAMPLE 26
The procedure of the image formation in Example 24 was repeated in
the same manner as in Example 24 except that the commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) employed in Example 24 was modified so as to
be capable of writing image with a resolution of 1200 dpi.
The result was that an image obtained by copying a monochrome
halftone image which was uniform in its entirety was uniform and
free of abnormal images as obtained in Example 24.
COMPARATIVE EXAMPLE 13
The procedure of the image formation in Example 26 was repeated in
the same manner as in Example 26 except that the photoreceptor
prepared in Comparative Example 11 was incorporated in the
commercially available copying machine (Trademark "Imagio Color
2800" made by Ricoh Company, Ltd.) employed in Example 26.
The result was that an image obtained by copying a monochrome
halftone image which was uniform in its entirety included streaks
running in the circumferential direction of the photoreceptor over
an about 50% area of the entire image area thereof.
EXAMPLE 27
A photoreceptor was prepared in the same manner as in Example 24
except that a 77th machined aluminum drum was employed and that the
thickness of the charge transport layer was changed to 14.3
.mu.m.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 24, From the profile, the power spectrum
thereof was prepared. The result was that in the power spectrum,
there were 6 peaks which satisfied
150.times.10.sup.-6.times.4096=0.614 or more in a region where n
satisfied ##EQU174##
namely in a region of 50.gtoreq.n.gtoreq.7.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 24.4.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 24.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 14
A photoreceptor was prepared in the same manner as in Comparative
Example 11 except that a 4th machined aluminum drum was employed
and that the thickness of the charge transport layer was changed to
14.3 .mu.m.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 24. From the profile, a power spectrum
thereof was prepared. In the power spectrum, there was only one
peak which satisfied 150.times.10.sup.-6.times.4096=0.614 or more
in a region where n satisfied ##EQU175##
namely in a region of 50.gtoreq.n.gtoreq.7.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 24.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image including streaks running in the
circumferential direction of the photoreceptor in an about 70% area
of the entire image area thereof.
EXAMPLE 28
100 aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a cutting tool with a 2.1 R diamond
point.
Of the thus machined aluminum drums, the profile of the outer
surface of a 85th machined aluminum drum was measured by use of a
surface roughness meter (Surfcom 1400A). As a result, a profile as
shown in FIG. 23 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIGS. 24 and 25 was prepared.
In the power spectrum, there were 9 peaks which satisfied
60.times.10.sup.-6.times.4096=0.246 or more in a region where n
satisfied ##EQU176##
namely in a region of 254.gtoreq.n.gtoreq.26.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 37.6.times.10.sup.-3.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TN-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
The surface of the undercoat layer was measured by use of the
surface roughness meter (Surfcom 1400A). As a result, a profile as
shown in FIG. 26 was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIGS. 27 and 28 was prepared.
In the power spectrum, there were 7 peaks which satisfied
45.times.10.sup.-6.times.4096=0.184 or more in a region where n
satisfied ##EQU177##
namely in a region of 254.gtoreq.n.gtoreq.26.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 14.0.times.10.sup.-3.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of a trisazo
pigment with the following formula were added, and the mixture was
dispersed for 48 hours: ##STR8##
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 3 hours. The
dispersion was then diluted with cyclohexanone, with stirring, in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid for the formation of a charge
generation layer and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the undercoat layer of the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge generation layer with a thickness of about 0.2
.mu.m was formed on the undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 90 parts by
weight of methylene chloride:
Parts by weight Charge transport material with the following
formula: 6 ##STR9## Polycarbonate resin (Trademark "Panlite K-1300"
made by 10 Teijin Limited) Silicone oil (Trademark "KF-50" made by
Shin-Etsu 0.002 Chemical Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
for the formation of a charge transport layer and then pulled up
vertically at a predetermined constant speed, whereby the coating
liquid for the formation of a charge transport layer was coated on
the surface of the charge generation layer of the aluminum
drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge transport layer with a thickness of about 24 .mu.m
was formed on the charge generation layer of the aluminum drum.
Thus, a photoreceptor of the present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm, and with writing image with a resolution of
400 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
EXAMPLE 29
A photoreceptor was prepared in the same manner as in Example 28
except that a 86th machined aluminum drum was employed and that the
thickness of the undercoat layer was changed to 6.0 .mu.m.
A profile of the surface of the undercoat layer and a power
spectrum thereof were prepared in the same manner as in Example
28.
In the power spectrum, there were 6 peaks which satisfied
45.times.10.sup.-6.times.4096=0.184 or more in a region where n
satisfied ##EQU178##
namely in a region of 254.gtoreq.n.gtoreq.26.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 12.2.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 28.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 15
A photoreceptor was prepared in the same manner as in Example 28
except that the cutting tool employed in Example 28 was replaced by
a cutting tool with a 1.6 R diamond point and that a 2nd machined
aluminum drum was employed.
A profile of the surface of the aluminum drum and a power spectrum
thereof were prepared in the same manner as in Example 28.
In the power spectrum, there were no peaks which satisfied
60.times.10.sup.-6.times.4096=0.246 or more in a region where n
satisfied ##EQU179##
namely in a region of 254.gtoreq.n.gtoreq.26.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 28.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image with streaks running in the
circumferential direction of the photoreceptor over an about 30%
area of the entire image area thereof.
COMPARATIVE EXAMPLE 16
A photoreceptor was prepared in the same manner as in Example 28
except that further 151 aluminum drums were machined and a 251st
machined aluminum was employed.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 28. From the profile, a power spectrum
thereof (not shown) was prepared. The result was that in the power
spectrum, there were 12 peaks which satisfied
60.times.10.sup.-6.times.4096=0.246 or more in a region where n
satisfies ##EQU180##
namely in a region of 254.gtoreq.n.gtoreq.26.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 11.5.times.10.sup.-3.
The thus prepared photoreceptor was incorporated in the same
copying machine as that employed in Example 28.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image free of streaks running in the
circumferential direction of the photoreceptor, but light and shade
streaks were slightly recognized near one end portion of the
image.
EXAMPLE 30
The procedure of the image formation in Example 28 was repeated in
the same manner as in Example 28 except that the copying machine
(Trademark "Imagio Color 2800" made by Ricoh Company, Ltd.)
employed in Example 28 was modified to as to be capable of writing
image with a resolution of 1200 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image was obtained.
COMPARATIVE EXAMPLE 17
The procedure of the image formation in Example 30 was repeated in
the same manner as in Example 30 except that the photoreceptor
employed in the copying machine in Example 30 was replaced by the
photoreceptor employed in Comparative Example 15.
When a monochrome halftone image which was uniform in its entirety
was copied and output by the copying machine, there was obtained an
image with streaks running in the circumferential direction of the
photoreceptor over an about 50% area of the entire image area
thereof.
EXAMPLE 31
A photoreceptor was prepared in the same manner as in Example 28
except that a 86th machined aluminum drum was employed and the
thickness of the charge transport layer was changed to 14.3
.mu.m.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 28. From the profile, a power spectrum
thereof (not shown) was prepared. The result was that in the power
spectrum, there were 13 peaks which satisfied
60.times.10.sup.-6.times.4096=0.246 or more in a region where n
satisfies ##EQU181##
namely in a region of 254.gtoreq.n.gtoreq.26.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 14.7.times.10.sup.-3.
The procedure of image formation in Comparative Example 15 was
repeated in the same manner as in Comparative Example 15 except
that the photoreceptor employed in the copying machine in
Comparative Example 15 was replaced by the above photoreceptor in
the copying machine.
When a monochrome halftone image which was uniform in its entirety
was copied and output by the copying machine, a uniform image free
of abnormal images such as the light and shade striped image was
obtained, and when a full-color landscape photograph was also
copied by.the copying machine, a high quality image was
obtained.
COMPARATIVE EXAMPLE 18
A photoreceptor was prepared in the same manner as in Comparative
Example 15 except that a 3rd machined aluminum drum was employed
and the thickness of the charge transport layer was changed to 14.3
.mu.m.
The procedure of the image formation in Comparative Example 17 was
repeated in the same manner as in Comparative Example 17 except
that the photoreceptor employed in the copying machine in
Comparative Example 17 was replaced by the above prepared
photoreceptor.
When a monochrome halftone image which was uniform in its entirety
was copied and output by the copying machine, there was obtained an
image with streaks running in the circumferential direction of the
photoreceptor over an about 75% area of the entire image area
thereof.
EXAMPLE 32
Three aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a diamond cutting tool.
The surface of the outer surface of the 2nd machined aluminum drum
was measured by use of a surface roughness meter (Surfcom 1400A).
As a result, a profile as shown in FIG. 29 was obtained.
The profile was mainly composed of a wave component with an
amplitude of about 0.15 .mu.m and a wave component with an
amplitude of about 0.4 .mu.m which were alternately repeated, so
that it was difficult to transform the profile to a sine wave.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum as shown
in FIG. 30 was prepared.
In the power spectrum, there was one strongest peak at n=15, with
(N.multidot..DELTA.t/n.sub.max)=4096.times.0.31/15=84.7 .mu.m.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 23.3.times.10.sup.-3.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of a trisazo
pigment with the following formula were added, and the mixture was
dispersed for 48 hours: ##STR10##
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 3 hours. The
dispersion was then diluted with cyclohexanone, with stirring, in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid for the formation of a charge
generation layer and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the undercoat layer of the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge generation layer with a thickness of about 0.2
.mu.m was formed on the undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 90 parts by
weight of methylene chloride:
Parts by weight Charge transport material with the following
formula: 6 ##STR11## Polycarbonate resin (Trademark "Panlite
K-1300" made by 10 Teijin Limited) Silicone oil (Trademark "KF-50"
made by Shin-Etsu 0.002 Chemical Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
for the formation of a charge transport layer and then pulled up
vertically at a predetermined constant speed, whereby the coating
liquid for the formation of a charge transport layer was coated on
the surface of the charge generation layer of the aluminum
drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge transport layer with a thickness of about 23 .mu.m
was formed on the charge generation layer of the aluminum drum.
Thus, a photoreceptor of the present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm, and with a writing pitch Wl of 63.5
.mu.m.
(N.multidot..DELTA.t /n.sub.max)W.sub.l =1.33. Hence, m=1 and
therefore 1.05 mW.sub.l =66.7 .mu.m. Thus, this copying machine
satisfied the relationship of
(N.multidot..DELTA.t/n.sub.max)>1.05 mW.sub.l.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 19
The procedure of the image formation in Example 32 was repeated in
the same manner as in Example 32 except that the copying machine
employed in Example 32 was modified so as to be capable of writing
with a writing pitch Wl of 42.3 .mu.m.
(N.multidot..DELTA.t /n.sub.max)/W.sub.l =84.7/42.3=2.00. Hence,
m=2. Therefore, 1.05 mW.sub.l 88.8 .mu.m, and 0.95 mW.sub.l =80.4
.mu.m. Thus, the copying machine did not satisfy the relationship
of either (N.multidot..DELTA.t/n.sub.max)>1.05 mW.sub.l or
(N.multidot..DELTA.t/n.sub.max)<0.95 mW.sub.l.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image with fine lengthwise streaks in the
entirety of the image.
COMPARATIVE EXAMPLE 20
A photoreceptor was prepared in the same manner as in Example 32
except that a 300th machined aluminum drum was employed, with 300
drums being machined, using the same diamond cutting tool as that
employed in Example 32.
A profile of the surface of the aluminum drum was prepared in the
same manner as in Example 32. n.sub.max was 15 (n.sub.max =15).
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 10.8.times.10.sup.-3.
The procedure of the image formation in Example 32 was repeated in
the same manner as in Example 32 except that the photoreceptor
employed in the copying machine in Example 32 was replaced by the
above photoreceptor.
This copying machine satisfied the relationship of
(N.multidot..DELTA.t/n.sub.max)>1.05 mW.sub.l.
When a monochrome halftone image which was uniform in its entirety
was copied and output by the copying machine, fine streaks as
produced in Comparative Example 19 were not produced in the image
obtained, but the obtained image was abnormal since it included
grained, light and shade streaks in the lower portion of the
image.
EXAMPLE 33
A photoreceptor was prepared in the same manner as in Example 32
except that when the aluminum drum was pulled upward from the
coating liquid for the formation of the charge transport layer in
the course of the formation of the charge transport layer, the
pulling speed was changed near the central portion of the aluminum
drum in such a manner that there was formed a difference of about
0.6 .mu.m in the thickness of the charge transport layer per about
15 mm length in the longitudinal direction of the
photoreceptor.
The procedure of the image formation in Example 1 was repeated in
the same manner as in Example 1 except that the photoreceptor in
the copying machine employed in Example 1 was replaced by the above
prepared photoreceptor.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image free of abnormal images such as the light and shade
striped image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 21
A photoreceptor was prepared in the same manner as in Example 33
except that the thickness of the undercoat layer was changed to
15.3 .mu.m.
The procedure of the image formation in Example 33 was repeated in
the same manner as in Example 33 except that the photoreceptor in
the copying machine employed in Example 33 was replaced by the
above prepared photoreceptor.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result,
there was obtained an image including abnormal light and shade
streaks in a lower portion of the image, although the image did not
include the fine lengthwise streaks as in Comparative Example
19.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
EXAMPLES 34 TO 36 AND COMPARATIVE EXAMPLE 22
The following four photoreceptors were prepared in the same manner
as in Example 32 except that the scanning speed of the cutting tool
was variously changed.
The procedure of the image formation in Example 32 was repeated in
the same manner as in Example 32 except that the photoreceptor in
the copying machine employed in Example 32 was replaced by each of
the above prepared photoreceptors.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. The results are
shown i-n the following TABLE 4:
TABLE 4 Comp. Ex. 34 Ex. 35 Ex. 36 Ex. 22 n.sub.max 17 16 13 10 (N
.multidot. .DELTA.t/n.sub.max) 74.7 79.4 97.7 127.0 I(S) 15.8
.times. 10.sup.-3 21.8 .times. 10.sup.-3 26.0 .times. 10.sup.-3
27.2 .times. 10.sup.-3 (N .multidot. .DELTA.t/n.sub.max) >
satisfied satisfied satisfied not 1.05 mW.sub.t or satisfied (N
.multidot. .DELTA.t/n.sub.max) < 0.95 mW.sub.t Image Quality
Normal Normal Normal fine streaks were observed in the entire image
area
EXAMPLE 37
Four aluminum drums with a diameter of 90 mm, a length of 352 mm,
and a wall thickness of 2 mm were prepared by machining the surface
of the aluminum drums, using a brand-new diamond cutting tool under
the same conditions.
The surface of the outer surface of each of the machined aluminum
drums was measured by use of a surface roughness meter (Surfcom
1400A), and a profile (not shown) was obtained with respect to each
of the machined aluminum drums.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum (not
shown) was prepared for each machined aluminum drum.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 33.5.times.10.sup.-3.
Since an acceptable standard I(S) for the surface of the aluminum
drum was set at 12.0.times.10.sup.-3 or more, the above four
aluminum drums were all found to be acceptable aluminum drums.
Formation of Undercoat Layer
A coating liquid for the formation of an undercoat layer was
prepared as follows:
Parts by weight Acrylic resin 15 (Trademark "ACRYDIC A-460-60" made
by Dainippon Ink & Chemicals, Incorporated) Melamine resin 10
(Trademark "Super Beckamine L-121-60" made by Dainippon Ink &
Chemicals, Incorporated)
The above components were dissolved in 80 parts by weight of methyl
ethyl ketone. To this solution were added 90 parts by weight of
titanium oxide powder (Trademark "TM-1" made by Fuji Titanium
Industry Co., Ltd.). This mixture was then dispersed in a ball mill
for 12 hours, whereby the coating liquid for the formation of an
undercoat layer was prepared.
The surface-roughened aluminum drum was immersed in the above
prepared coating liquid and then pulled up vertically at a
predetermined constant speed, whereby the coating liquid was coated
on the surface of the aluminum drum.
With the posture of the aluminum drum maintained, the aluminum drum
was transported into a drying chamber, where the aluminum drum was
dried at 140.degree. C. for 20 minutes, whereby an undercoat layer
with a thickness of 3.5 .mu.m was formed on the aluminum drum.
The surface of the surface of the undercoat layer was measured by
use of a surface roughness meter (Surfcom 1400A), and a profile
thereof (not shown) was obtained.
From this profile, sampling was conducted with .DELTA.t=0.31 .mu.m,
and N=4096, and the thus obtained samples were subjected to
discrete Fourier transformation, whereby a power spectrum (not
shown) was prepared.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 22.7.times.10.sup.-3.
Since an acceptable standard I(S) for the surface of the undercoat
layer was set at 6.0.times.10.sup.-3 or more, the above undercoat
layer was found acceptable.
Formation of Charge Generation Layer
15 parts by weight of butyral resin (Trademark "S-Lec BLS" made by
Sekisui Chemical Co., Ltd.) were dissolved in 150 parts by weight
of cyclohexanone. To this solution, 10 parts by weight of a trisazo
pigment with the following formula were added, and the mixture was
dispersed for 48 hours: ##STR12##
To the above dispersion, 210 parts by weight of cyclohexanone were
further added, and the mixture was dispersed for 3 hours. The
dispersion was then diluted with cyclohexanone, with stirring, in
such a manner that the amount ratio of the solid components in the
dispersion was 1.5 wt. %, whereby a coating liquid for the
formation of a charge generation layer was prepared.
The aluminum drum with the undercoat layer was immersed in the
above prepared coating liquid for the formation of a charge
generation layer and then pulled up vertically at a predetermined
constant speed, whereby the coating liquid was coated on the
surface of the undercoat layer of the aluminum drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge generation layer with a thickness of about 0.2
.mu.m was formed on the undercoat layer of the aluminum drum.
Formation of Charge Transport Layer
A coating liquid for the formation of a charge transport layer was
prepared by dissolving the following components in 90 parts by
weight of methylene chloride;
Parts by weight Charge transport material with the following
formula: 6 ##STR13## Polycarbonate resin (Trademark "Panlite
K-1300" made by 10 Teijin Limited) Silicone oil (Trademark "KF-50"
made by Shin-Etsu 0.002 Chemical Co., Ltd.)
The aluminum drum with the undercoat layer and the charge
generation layer was immersed in the above prepared coating liquid
for the formation of a charge transport layer and then pulled up
vertically at a predetermined constant speed, whereby the coating
liquid for the formation of a charge transport layer was coated on
the surface of the charge generation layer of the aluminum
drum.
The coating liquid coated aluminum drum was dried in the same
manner as for the undercoat layer at 120.degree. C. for 20 minutes,
whereby a charge transport layer with a thickness of about 23 .mu.m
was formed on the charge generation layer of the aluminum drum.
Thus, a photoreceptor of the present invention was prepared.
The thus prepared photoreceptor was incorporated in a commercially
available copying machine (Trademark "Imagio Color 2800" made by
Ricoh Company, Ltd.) capable of writing with writing light with a
wavelength of 780 nm, and with a resolution of 400 dpi.
By use of this copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output. As a result, a
uniform image was obtained.
Furthermore, a full-color landscape photograph was also copied by
use of this copying machine. As a result, a high quality image was
obtained.
COMPARATIVE EXAMPLE 23
A photoreceptor was prepared in the same manner as in Example 1
except that 501 drums were machined by use of the diamond cutting
tool used in Example 37, and a 501st machined aluminum drum was
used.
The surface of the outer surface of the 501st machined aluminum
drum was measured by use of a surface roughness meter (Surfcom
1400A), and a profile thereof (not shown) was obtained.
From the profile, a power spectrum (not shown) was prepared. The
integrated value of the power spectrum, I(S), was then calculated.
The result was that I(S) was 10.8.times.10.sup.-3.
Since an acceptable standard I(S) for the surface of the aluminum
drum was set at 12.0.times.10.sup.-3 or more as in Example 37, the
above aluminum drums was found to be unacceptable. However, by use
of this aluminum drum, the photoreceptor was prepared in the same
manner as in Example 1 as mentioned above.
With respect to the undercoat layer, a profile thereof (not shown)
was also obtained in the same manner as in Example 37, and a power
spectrum (not shown) was prepared from the profile.
The integrated value of the power spectrum, I(S), was then
calculated. The result was that I(S) was 5.3.times.10.sup.-3.
Since an acceptable standard I(S) for the surface of the undercoat
layer was set at 6.0.times.10.sup.-3 or more, the above undercoat
layer was found unacceptable. However, this undercoat layer was
used in the preparation of the photoreceptor.
The procedure of the image formation in Example 37 was repeated in
the same manner as in Example 37 except that the photoreceptor
employed in Example 37 was replaced by the above prepared
photoreceptor.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the copying machine
using the photoreceptor, there was obtained such an image that
appeared to include slight uneven light and shade stripes near the
edge portion of the image. When a full-color landscape photograph
was also copied by use of the copying machine, there was obtained
such an image that was found to include slight uneven light and
shade portions near the edge portion of the image by close
observation.
EXAMPLE 38
The procedure of the image formation in Example 37 was repeated in
the same manner as in Example 37 except that the copying machine
(Trademark "Imagio Color 2800" made by Ricoh Company, Ltd.)
employed in Example 37 was modified so as to be capable of writing
with a resolution of 1000 dpi.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the modified copying
machine, a uniform image free of abnormal images such as the light
and shade striped image was obtained, and when a full-color
landscape photograph was also copied by use of the copying machine,
a high quality image was obtained.
COMPARATIVE EXAMPLE 24
The procedure of the image formation in Example 2 was repeated in
the same manner as in Example 2 except that the photoreceptor
employed in the copying machine in Example 2 was replaced by the
photoreceptor prepared in Comparative Example 23.
As a result, when a monochrome halftone image which was uniform in
its entirety was copied and output by use of the copying machine
using the photoreceptor, an image with 4 sets of light and shade
stripes in a band shape near the edge portion of the image was
obtained. Furthermore, light and shade stripes with a light-grained
pattern, were also recognized in the image.
When the same full-color landscape photograph as used in Example 37
was also copied by use of the copying machine, an image including
band-shaped abnormal images near the edge portion of the image was
obtained. In the obtained color image, the portion in a position
which almost corresponded in terms of the height to the portion of
the grained light and shade stripes recognized, when the monochrome
half tone image was copied, partially included a slightly unnatural
color tone portion.
EXAMPLE 39
1000 aluminum drums with the same size as that of the aluminum drum
employed in Example 38 were machined, using a brand-new diamond
cutting tool of the same type as that of the diamond cutting tool
employed in Example 38.
A profile of the surface of each of the machined aluminum drums was
measured and I(S) of each aluminum drum was measured in the same
manner as in Example 37.
An acceptable standard I(S) of the aluminum drum was set at
12.0.times.10.sup.-3 or more, so that when the I(S) of any of the
machined aluminum drums was found not to meet the standard I(S),
the machining was stopped and the diamond cutting tool was replaced
with a brand-new diamond cutting tool. Specifically, the I(S) of a
387th aluminum drum and a 819th aluminum drum were found to be less
than 12.0.times.10.sup.-3 in the course of the machining process,
the diamond cutting tool was replaced with a brand-new diamond tool
two times.
By use of the above prepared 1000 machined aluminum drums, 1000
photoreceptors were continuously produced in the same manner as in
Example 38. Each of the photoreceptors included the undercoat
layer, the charge generation layer and the charge transport layer
as in the photoreceptor prepared in Example 38.
The thus produced 1000 photoreceptors were grouped into 20 lots,
each lot consisting of 50 photoreceptors. One photoreceptor was
picked up at random from each lot, and each of the picked up
photoreceptors was incorporated in the copying machine used in
Example 3.
By use of the copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output to check whether
or not any abnormal images such as the light and shade striped
image were formed. The result was that no abnormal images such as
the light and shade striped image were formed by any photoreceptor
in the 20 lots.
COMPARATIVE EXAMPLE 25
20 aluminum drums with the same size as that of the aluminum drum
employed in Example 39 were machined, by use of the diamond cutting
tool which was used first in Example 39, that is, the diamond
cutting tool which was used before it was replaced when the 387th
aluminum drum was machined.
I(S) of all of the machined aluminum drums was measured in the same
manner as in Example 39.
Only a second machined aluminum drum had an I(S) of
12.7.times.10.sup.-3, while the I(S) of the other 19 aluminum drums
was less than 12.0.times.10.sup.-3.
By use of the above prepared 20 machined aluminum drums, 20
photoreceptors were produced in the same manner as in Example 39.
Each of the photoreceptors included the undercoat layer, the charge
generation layer and the charge transport layer as in the
photoreceptor prepared in Example 39.
Each of the photoreceptors was incorporated in the copying machine
used in Example 39.
By use of the copying machine, a monochrome halftone image which
was uniform in its entirety was copied and output to check whether
or not any abnormal images such as the light and shade striped
image were formed. The result was that 19 copying machines produced
abnormal images including the light and shade stripes. In
particular, all of the copying machines, in which the aluminum
drums machined at the 7th and after machining were incorporated,
conspicuously produced abnormal light and shade striped images.
Japanese Patent Application No. 2000-004008 filed Jan. 12, 2000,
and Japanese Patent Application No. 2000-006769 filed Jan. 14, 2000
are hereby incorporated by reference.
* * * * *